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Internet Engineering Task Force                       Hemant Agrawal
Internet Draft                               Telverse Communications
draft-agrawal-sip-h323-interworking-01.txt             Radhika R Roy
July 13, 2001                                                   AT&T
Expires: Jan 2002                                      Vipin Palawat
                                                   Cisco Systems Inc
                                                       Alan Johnston
                                                        MCI WorldCom
                                                       Charles Agboh
                                                               Ebone
                                                          David Wang
                                            Nuera Communications Inc
                                                 Henning Schulzrinne
                                                        Kundan Singh
                                                 Columbia University
                                                          Joon Maeng
                                                        ipDialog Inc


                       SIP-H.323 Interworking

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC 2026 [1]. Internet-Drafts are
working documents of the Internet Engineering Task Force (IETF), its
areas, and its working groups. Note that other groups may also
distribute working documents as Internet-Drafts. Internet-Drafts are
draft documents valid for a maximum of six months and may be
updated, replaced, or obsoleted by other documents at any time. It
is inappropriate to use Internet- Drafts as reference material or to
cite them other than as "work in progress."

The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

This document is a product of the SIP-H.323 Interworking Working
Group of the Internet Engineering Task Force (IETF).  Comments should
be submitted to the mailing list sip-h323@yahoogroups.com.com.

Copyright Notice

   Copyright (c) The Internet Society (2000). All Rights Reserved.


Abstract

This document describes the interworking between SIP and H.323
protocol. It defines the the logical entity known as the SIP-H.323
Interworking Function (SIP-H.323 IWF) that will allow the interworking
between the SIP (Session Initiation Protocol) and H.323  protocol.
This includes the call sequence mapping, message parameter mapping,
translation between H.245 and SDP, state machines, and handling of
different call procedures.



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Table of Contents

1. Terminology
2. Introduction
3. Background
4. Scope of the document
5. Definitions
6. Overview of IWF Functionality
7. Interworking Requirements for IWF
8.Mapping Between SIP and H.323 in IWF
8.1. Alias Addresses Mapping
8.1.1. Converting SIP Addresses to H.323 Addresses
8.1.2. Converting H.323 Addresses to SIP Addresses
8.2 Message Mapping
8.3 Call Sequence Mapping
8.4 Message Parameters Mapping
8.5 Audio/Video Formats Mapping
9. Basic Message Handling
9.1 Handling of H.323 Signaling Messages
9.2 Handling of SIP Signaling Messages
10.Interworking Call Scenarios for Different Configurations
11. State Machine
12. Implementation Requirements
13. Activities Planned for Next Phase
14. Security Considerations
15. Known Issues
16. To Be Done
17. Conclusion

Appendix A: Calculating common subset of capabilities
Appendix B: Modification in ASN.1 syntax of H.225
Appendix C: Call Flow Message Details
Appendix D: Summary of SIP-H.323 Interworking Requirements

References
Acknowledgments
Authors' Addresses
Full Copyright Statement



1 Terminology

In this document, the key words "MUST", "MUST NOT", "REQUIRED",
"SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
and "OPTIONAL" are to be interpreted as described in RFC 2119 [2]
and indicate requirement levels for compliant implementations.

2. Introduction

The primary objective of SIP-H.323 Interworking function (IWF) is to
provide protocol conversion between SIP and H.323 protocol. Both of
these protocols use similar formats (e.g. RTP) to transfer media
(audio/video/data) over the Packet Network. It is, therefore, required


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to perform the mapping between SIP and H.323 signaling messages only
to achieve the interworking between the two protocols. The objective is
to transmit media end-to-end directly between the two end systems in
H.323 and SIP networks. However, some of the special scenarios may
require media to be routed through the IWF using MSF. Such scenarios
are out of the scope of the current document.


The logical relationship between the IWF and other SIP and H.323
entities is shown in Figure 1.





  H.323 Entity                              SIP Entity

+---------------+
| H.323 GK      |                        +----------------+
|               |\                       | SIP |
+---------------+ \                      |    Server      |
                   \                    /+----------------+
                    \                  /
+---------------+    +---------------+/
| H.323 MCU     |----|  Interworking |
| MC,or Terminal|    |   Function    |
+---------------+    +---------------+\
                    /                  \
                   /                    \+----------------+
+---------------+ /                      |     SIP        |
| H.323 Gateway |/                       |  User Agent    |
|               |                        +----------------+
+---------------+

Figure 1 : Logical Relationship between IWF and SIP/H.323 entities


3. Background

Two standards are currently popular for IP telephony signaling:  the
H.323 protocol suite by ITU-T, and the Session Initiation Protocol
(SIP) by IETF. Both of these signaling protocols provide mechanisms for
call establishment and teardown, call control and supplementary services,
and capability exchange. In terms of functionality and
services that can be supported, H.323 version 2 [5] and SIP Version 2
[3] are very similar. However, supplementary services in H.323 are quite
different from SIP.

H.323 and SIP are improving themselves and the differences between them are
diminishing with each new version. At present, H.323 and SIP networks are
coexisting with different service providers in many parts of the world as
they think to provide services to satisfy their customers' needs.



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+-----------+--------+--------+-------+--------+---------+------+
| H.225     |        |        |       |  H.225 | Codecs  |      |
| Call      |  SDP   |  H.245 |  SIP  |  RAS   |-------- | RTCP |
| Signaling |        |        |       |        | RTP     |      |
+-----------+--------+--------+---+---+--------+---------+------+
|                                 |                             |
|          TCP                    |            UDP              |
|                                 |                             |
+-----------+--------+--------+-------+--------+---------+------+
|                                                               |
|                                IP                             |
|                                                               |
+-----------+--------+--------+-------+--------+---------+------+
|                                                               |
|                     Linked and Physical Layer                 |
|                                                               |
+-----------+--------+--------+-------+--------+---------+------+


       Figure 2: SIP and H.323 Protocol stacks

SIP-H.323 IWF is a solution for those service providers who want to
support both H.323 and SIP networks. There are different forums
involved in the standardization of SIP-H.323 IWF. The aim of all these
forums is to provide an agreed upon specifications so that there will
be no interoperability issues between different vendor implementations.
This work is also under progress in ETSI TIPHON and IMTC aHit! forums.

4. Scope of this document

This document describes interworking between H.323 Version 2.0 [5] and
SIP Version 2.0 [3]. However, since H.323v2 terminal may or may not
support FastConnect, solutions without using this feature are also
detailed in this document.

This Interworking recommendation is being defined in two phases. The
Current (first) phase  defines the basic call establishment, call
termination. It also defines the translation between H.245 and SDP for
session description. The second phase will include optional messaging
of the two protocols, advanced features and services. Both phases have
to meet the general requirements specified in the SIP-H323 Interworking
Requirement draft [9].

The support for future versions of H.323 and SIP MAY be addressed in
the next phase.

5. Definitions

 Endpoint (EP): This is an entity from which the media originates or
finally terminates. This can either be H.323 terminal or SIP user
agent.




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H.323 Gatekeeper (GK) : The Gatekeeper (GK) is an OPTIONAL H.323 entity
on the network that provides address translation and controls access to
the network for H.323 terminals, Gateways and MCUs. The Gatekeeper may
also provide other services to the terminals, Gateways and MCUs such as
bandwidth management and locating Gateways.

H.323 Terminal:  A H.323 Terminal is an endpoint on the network which
provides the real-time, two-way communications with another H.323
terminal, Gateway, or Multipoint Control Unit. This communication
consists of control, indications, audio, moving color video pictures,
and/or data between the two terminals. A terminal may provide speech
only, speech and data, speech and video, or speech, data and video.

H.323 Side: The H.323 side of the IWF is the part of the IWF that
terminates and originates H.323 signaling from and to the H.323 network
respectively.

Interworking Function (IWF): It allows interworking between the H.323
and SIP networks.

Media Switching Function (MSF): This is an OPTIONAL logical entity
present in the IWF, which will perform the task of witching/transcoding RTP
from one logical port to other.

SIP User Agents (UA): A logical entity which can act as both SIP user
agent client and SIP user agent server.

SIP Server: This can be either SIP Proxy, Redirect, Location or
Registrar server.

SIP Proxy Server: A logical entity which acts as both server and a
client. SIP messages will be processed and passed to other SIP
entities. A SIP proxy server interprets, and, if necessary, rewrites a
SIP message before forwarding it.


SIP Redirect Server: A logical entity which is primarily used for
address translation and locating a SIP user. It may take the help of
location server for locating a SIP user. SIP redirect server does not
accept calls and does not initiate a SIP request on behalf of a calling
SIP endpoint. SIP redirect server sends a response to a request for
locating a SIP user.

SIP Location Server: A location service is used by a SIP proxy or SIP
redirect server to obtain information about the callee's possible
location(s).

SIP Registrar Server: A SIP registrar is a server that accepts REGISTER
requests from SIP endpoints. A SIP registrar is typically co-located
with a SIP proxy or SIP redirect server and MAY make its information
available through the location server.




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SIP Side: The SIP side of the IWF is the part of the IWF that
terminates and originates SIP signaling from and to the SIP network
respectively.


6. Overview of IWF Functionality

When the IWF receives call signaling messages from an H.323 entity, it
performs the necessary translation and sends the corresponding equivalent
messages to SIP entity on the SIP side of the IWF and vice versa. The IWF
SHALL provide signaling translation for all phases of a call.

This IWF does not include media format conversion. However, it MAY
include a Media Switching Function for switching RTP packets which is
out of scope of this document.

              +---------------------------------------+
              |         +--------------------+        |
              |         |      SIP-H.323     |        |
              |         |    Interworking    |        |
              |         |      Function      |        |
              |         +--------------------+        |
              |           /              \            |
              |  +---------------+ +---------------+  |
              |  |               | |               |  |
              |  |  H.323 Stack  | |  SIP Stack    |  |
              |  |               | |               |  |
              |  +---------------| +---------------+  |
              +---------------------------------------+
                 /                                 \
        +-------------+                        +------------+
        |             |                        |            |
        |    H.323    |       Media Flow       |    SIP     |
        |   Network   |========================|   Network  |
        +-------------+                        +------------+

            Figure 3: Overview of the IWF



There are several scenarios where SIP-H.323 IWF can be placed with
different network elements in the SIP and H.323 networks. The way the
messages are generated during a call establishment between H.323 EP and
a SIP UA, is different depending on the scenario.

Scenario 1: IWF without H.323 GK and SIP Server

+----------+                  +--------+                   +--------+
|          |                  |        |                   |        |
| H.323 EP |<---------------->|   IWF  |<----------------->| SIP UA |
|          |                  |        |                   |        |
+----------+                  +--------+                   +--------+



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Scenario 2: IWF with H.323 GK and without SIP Server

+----------+   +----------+   +--------+                  +---------+
|          |   |          |   |        |                  |         |
| H.323 EP |<->| H.323 GK |<->|   IWF  |<---------------->| SIP UA  |
|          |   |          |   |        |                  |         |
+----------+   +----------+   +--------+                  +---------+

Scenario 3: IWF with SIP Server and without SIP Server

+----------+                  +--------+   +----------+   +---------+
|          |                  |        |   | Proxy or |   |         |
| H.323 EP |<---------------->|   IWF  |<->| Redirect |<->| SIP UA  |
|          |                  |        |   |  Server  |   |         |
+----------+                  +--------+   +----------+   +---------+



Scenario 4: IWF with H.323 Server and SIP Server
+------_---+   +----------+   +--------+   +----------+   +--------+
|          |   |          |   |        |   | Proxy or |   |        |
| H.323 EP |<->| H.323 GK |<->|   IWF  |<->| Redirect |<->| SIP UA |
|          |   |          |   |        |   |  Server  |   |        |
+----------+   +----------+   +--------+   +----------+   +--------+


The IWF can be configured manually similar to SIP servers , H.323 GKs and GWs
or one can use DNS SRV or DNS.


7. Interworking Requirements for IWF

The requirement for SIP-H.323 IWF has already been addressed in detail
in "SIP-H.323 Interworking Requirements" [9]. The summary of SIP-H.323
interworking requirements is given for reference in Appendix D.

8. Mapping Between SIP and H.323 in IWF

8.1. Addresses Mapping

There are different formats of alias addresses in H.323 and the
corresponding addresses in SIP.

H.323 Version 2 supports the following schemes of alias addresses:
H323Id, E164Id, Email Id, url Id, transport Id and partyNumber

  H.323 Version 1 supports only H323Id and E164Id.

  The ASN.1 description of an H.323 Alias Address in H.323 Version 2
  is:

  H323-Alias-Address ::= CHOICE
   {


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     e164    IA5String (SIZE(1..128)) (FROM("0123456789#*,")),
     h323-ID BMPString (SIZE (1..256)),
     ...,
     url-ID  IA5String ( SIZE(1 .. 512)),-- URL Style address
     transport-ID TransportAddress,  -- IPv4, IPv6, IPX etc.,...
     email-ID IA5String (SIZE(1..512)),
                         -- rfc822 compliant email address
     partyNumber PartyNumber
   }
  The PartyNumber parameter that contains public numbering plan or
  data/telex/private/public numbering digits is not described in this
  document and is left for further study.

  On the other hand, SIP address  can be defined by the following
  BNF from the description provided in RFC 2543 [3]:

      SIP-Address    -  (name-addr | addr-spec)
        name-addr    -  [display-name] "<" addr-spec ">"
        addr-spec    -  SIP-URL|URI
        SIP-URL      -  "sip:"[userinfo"@"]hostport url-parameters
                          [headers]
      userinfo       -  [user|telephone-subscriber][":"password]
        user         -  *(unreserved|escaped|"&"|"="|"+"|"$"|","
                          |";"|"?"|"/")
      password       -  *(unreserved|escaped|"&"|"="|"+"|"$"|",")
      hostport       -  host[":"port]
        host         -  hostname|Ipv4address|IPV6reference

      hostname       = *( domainlabel "." ) toplabel [ "." ]
      domainlabel    = alphanum | alphanum *( alphanum | "-" ) alphanum
      toplabel       = alpha | alpha *( alphanum | "-" ) alphanum
      IPv4address    = 1*digit "." 1*digit "." 1*digit "." 1*digit
      port           = *digit
      url-parameters -  *(";"url-parameter)
      url-parameter  -  transport-param | user-param | method-param |
                         ttl-param | maadr-param | other-param
      ttl            = 1*3DIGIT       ; 0 to 255
      maddr-param    = "maddr=" host
      user-param     = "user=" ( "phone" | "ip" )
      method-param   = "method=" Method
      other-param    = ( token | ( token "=" ( token | quoted-string
                         )))
      headers        = "?" header *( "&" header )
      header         = hname "=" hvalue
      hname          = 1*uric
      hvalue         = *uric
      uric           = reserved | unreserved | escaped
      reserved       = ";" | "/" | "?" | ":" | "@" | "&" | "=" | "+" |
                       "$" | ","
      digits         = 1*DIGIT

   The SIP URI components can be described as stated below :




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   telephone-subscriber  = global-phone-number | local-phone-number
   global-phone-number   = "+" 1*phonedigit [isdn-subaddress]
                             [post-dial]
   local-phone-number    = 1*(phonedigit | dtmf-digit |
                             pause-character) [isdn-subaddress]
                             [post-dial]
   isdn-subaddress       = ";isub=" 1*phonedigit
   post-dial             = ";postd=" 1*(phonedigit | dtmf-digit
                         |  pause-character)
   phonedigit            = DIGIT | visual-separator
   visual-separator      = "-" | "."
   pause-character       = one-second-pause | wait-for-dial-tone
   one-second-pause      = "p"
   wait-for-dial-tone    = "w"
   dtmf-digit            = "*" | "#" | "A" | "B" | "C" | "D"

  Alias address are mapped based on procedures described in the
  subsequent sections.


8.1.1. Converting SIP Addresses to H.323 Addresses

* E164

SIP URL which contains the "user=phone" and does not contain a "w"
in the user part will be mapped to E164 Id of H323. The e164 field only
allows characters from the set "0123456789#*,". Thus, any leading "+"
is removed from the SIP telephone-subscriber part, as are any visual
separators "-" and ".".
For example: +1-978-985-7193 will be converted to "19789857193". The
pause "p" is replaced with ",".

If the phone number exceeds 128 characters, the IWF generates a SIP
response of 414 (Request-URI Too Long). E164 in H.323 can be either
E.164 number in H.323 Alias Address or it may also be derived from the
caller/callee number in Q.931 messages. Thus, SIP URL with phone numbers may
also be mapped to caller/callee number in Q.931 messages.

SIP URL which do not contain "user=phone", but contains numerical digits in
user part may be converted to E164 numbers.

The conversion of tel Url to E164 number is for further discussion.


* H323Id

In most of the cases, userinfo part of SIP URL will be mapped to
H323 Id of H323.  Each BMP character in h323-ID stores the
corresponding text character in the SIP Address. (BMP stands for basic
multilingual plane i.e., Basic ISO/IEC 10646-1 (unicode) character
set).



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The h323-ID MUST always be generated so that a terminal running version
1.0 of H.323 (which supports only e164 and h323-ID, but does not support
transport-ID, url-ID or email-ID) can still decode the address.

If the SIP-Address contains more than 256 characters, only the addr-
spec  part is copied. If the addr-spec exceeds 256 characters, the IWF
generates a SIP response of 414 (Request-URI Too Long).


* Email Id


If the SIP URL looks like an Email Id i.e. user@group, then it will
be mapped to Email Id of H323. To indicate an email-like address, an
H.323v1 entity shall send it in H323-ID and prefix it with the seven
characters "mailto:". In this case the string after the colon must be
an RFC 822 compliant email address.
An example of such an address is as follows:
                  mailto:abc@company.com

If the size exceeds 512 characters, the IWF generates the SIP status
414  (Request-URI Too Long).


* Transport Id

If the SIP URL contains the IPv4 address in the host part, then it
will be mapped to the transport Id of H323. To indicate an IP-like
address, an H.323v1 entity shall send it in H323-ID and prefix it with
the three characters "ip:". In this case the string after the colon
must contain an address in dotted decimal form, with an optional colon
and port number at the end. An example of such an address is as
follows:  ip:10.0.0.1:5050. If a port parameter is present in the SIP
address, the number is used. Otherwise, the port number depends on the
context. For example, for the destination address of H.323 SETUP
messages, it is set to 1720, otherwise it is set to 0.

* Url Id

If the SIP URL looks like a url i.e., user@domain, then it will be
mapped to the url Id of H323. If the SIP URL exceeds 512 bytes in size,
the IWF generates the SIP status 414 (Request-URI too long).

Examples of Address Resolution

        o The SIP Address "sip:j.doe@big.com" is converted to
                H.323 Address: {
                         h323-ID = "sip:j.doe@big.com",
                         url-ID  = "sip:j.doe@big.com",
                         email-ID= "j.doe@big.com"
                 }




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        o The SIP Address "sip:+1-212-555-1212:1234@iwf.com;
          user=phone" is converted to
                  H.323 Address: {
                         e164    = "12125551212",
                         h323-ID = "sip:+1-212-555-1212:1234@iwf.com",
                         url-ID  = "sip:+1-212-555-1212:1234@iwf.com",
                         email-ID= "+1-212-555-1212:1234@iwf.com"
                  }

        o The SIP Address "sip:alice@10.1.2.3" is converted to
                  H.323 Address: {
                          h323-ID     = "sip:alice@10.1.2.3",
                          url-ID      = "sip:alice@10.1.2.3",
                          tranport-ID = IPAddress 10.1.2.3:1720,
                          email-ID    = "alice@10.1.2.3"
                  }

        o The SIP Address "A. Bell <sip:a.g.bell@bell-tel.com>" is
          converted to H.323 Address: {
                                h323-ID  = "A. Bell<sip:a.g.bell@bell-
              tel.com>",
                           url-ID   = "sip:a.g.bell@bell-tel.com",
                           email-ID = "A. Bell <a.g.bell@bell-tel.com>"
                       }


8.1.2. Converting H.323 Addresses to SIP Addresses

*E164 Id

It will be put in a SIP URL with a telephone number. The number
will either be globalized or left as a local number in which case it
will require the  information of From header. "phone-context" is used
to  represent the local number.
      sip:telephone-subscriber@host; user=phone

     For Example:  E164Id = +1-719-227-9665 can be mapped to
                   sip:+1-719-227-9665@host;user=phone


'host' is a host name (domain name of IPv4 address) followed by
an optional port number. It is a mandatory in SIP URL. The E164 Id in
H.323 does not provide any direct information of the host part of the
SIP URL (the host part should identify a SIP server with the IPv4
address of the domain name). The host part may be determined using some
specialized service either by location server or by pre-provisioning in
IWF.

If Called/Calling Party Number is present in H.323 messages (other
than UUIE part of Q.931 message), it may be treated like a E164 Id and
mapping may be done as discussed above.

The mapping of E164 address to tel Url is for further discussion.



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*H323Id

It will be mapped to userinfo part of SIP URL. If the H323 Id is similar to
"mailto:user@domain", then it should be mapped to SIP URL after replacing
"mailto:" with "sip:"

However for the cases where H323 Id  is in the form of an email id  with
fully qualified domain name, it may be used as a SIP URL.  However,  it shall
not result into more than one '@' in the SIP URL.


*EmailId

It will be mapped to SIP-URL/URI after adding the "sip:" prefix.
For Example: email ID = userA@gateway.iwf.com will be mapped to
     sip:userA@gateway.iwf.com


*UrlId

It  will be mapped to SIP URL after adding the "sip" prefix if it
is not present in the url Id.
For Example: url Id = h225://userA@gateway.iwf.com:2030 will be
mapped to sip:userA@gateway.iwf.com:2030


*Transport Id

It will be mapped to host part of SIP URL if it is a IPv4 address.
User part of SIP URL in this case may be mapped to either H323 Id,
Email Id or E164 Id. If no port is specified then the default port
number 5060 will be used.  The IWF  SHOULD not map transport Id to SIP
URL if it corresponds to the IP address of IWF itself. In this case,
the other aliases will reflect the callee address.
     For Example: Transport Id = 164.164.28.132 can be mapped to
sip:164.164.28.132:5060
     Transport Id = 164.164.28.132:2030 can be mapped to
sip:164.164.28.132:2030

Zone prefix in H.323 non-standard parameter of registration MAY be used
during address resolution on H.323 Gatekeeper.  This will be further
discussed in next release of this draft.

In cases  with no H.323 Address, the H.323 Transport Address (TSAP) may be
used for the   SIP Url with the user name as "Unknown". The H.323 call
signaling port, if default should be coverted into default SIP port address.
For example. H.323 destination address 198.192.12.35:1720 can be converted
into  sip:unknown@198.192.12.35:5060







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8.2. Message Mapping

Some of the SIP and H.323 messages have direct one to one mappings.
These are listed below. These tables hold good for both conversions
i.e. SIP messages to H.323  messages and vice versa.


  SIP  Message                     H.323 Message
  ------------                     -------------
  INVITE                           SETUP (without GK in network)
  INVITE                           ARQ   (with GK in network)
  OPTIONS(Accept:application/sdp)  H.245 Send Terminal Capability Set
  180  Ringing                     H.225 Alerting
  183  Session Progress            H.225 Alerting/Progress
  300  Multiple Choices            H.225 ReleaseComplete
                                   (reason=undefinedReason)
  301  Moved Permanently           ACF with updated Address
                                   of SIP's Contact header field
                                   (If GK is present) or update
                                   local lookup table.
  302  Moved Temporarily           ACF with updated Address
                                   of SIP's Contact header field
                                   (If GK is present) or update
                                   local lookup table.
  380  Alternative Service         H.225 Facility
  400  Bad Request                 H.225 ReleaseComplete
                                   (reason=undefinedReason)
  401  Unauthorized                H.225 ReleaseComplete
                                   (reason=securityDenied)
  402  Payment Required            H.225 ReleaseComplete
                                   (reason=undefinedReason
                                   /noPermission)
  403  Forbidden                   H.225 ReleaseComplete
                                   (reason=noPermission
                                    /destinationRejection)
  404  Not Found                   H.225 ReleaseComplete
                                   (reason=unreachableDestination)
  405  Method Not Allowed          H.225 ReleaseComplete
                                   (reason=undefinedReason)
  406  Not Acceptable              H.225 ReleaseComplete
                                   (reason=undefinedReason)
  407  Proxy Auth. Required        H.225 Release Complete
                                   (reason=securityDenied)
  408  Request Timeout             H.225 ReleaseComplete
                                   (reason=adaptiveBusy)
  409  Conflict                    H.225 ReleaseComplete
                                   (reason=undefinedReason)
  410  Gone                        H.225 ReleaseComplete
                                   (reason=unreachableDestination)
  411  Length Required             H.225 ReleaseComplete
                                   (reason= undefinedReason)
  413  Request Entity Too Large    H.225 ReleaseComplete
                                   (reason=badFormatAddress)
  414  Request-URI Too Large       H.225 ReleaseComplete
                                   (reason=badFormatAddress)
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  415  Unsupported Media Type      H.225 ReleaseComplete
                                   (reason=undefinedReason)
  420  Bad Extension               H.225 ReleaseComplete
                                   (reason=badFormatAddress)
  480  Temporarily not available   H.225 ReleaseComplete
                                   (reason=adaptiveBusy)
  481  Call Leg/Transaction        H.225 ReleaseComplete
       Does Not Exist              (reason=undefinedReason)
  482  Loop Detected               H.225 ReleaseComplete
                                   (reason=undefinedReason)
  483  Too Many Hops               H.225 ReleaseComplete
                                   (reason=undefinedReason)
  484 Address incomplete           H.225 ReleaseComplete
                                   (reason=badFormatAddress)
  485  Ambiguous                   H.225 ReleaseComplete
                                   (reason= undefinedReason)
  486  Busy Here                   H.225 ReleaseComplete
                                   (reason=inConf)
  487  Request Terminated          H.225 ReleaseComplete
                                   (reason=undefinedReason)
  488  Not Acceptable Here         H.225 ReleaseComplete
                                   (reason=undefinedReason)
  500  Server Internal Error       H.225 ReleaseComplete
                                   (reason=undefinedReason)
  501  Not Implemented             H.225 ReleaseComplete
                                   (reason=undefinedReason)
  502  Bad Gateway                 H.225 ReleaseComplete
                                   (reason=gatewayResources)
  503  Service Unavailable         H.225 ReleaseComplete
                                   (reason=gatewayResources)
  504  Server Time-out             H.225 ReleaseComplete
                                   (reason=adaptiveBusy)
  505  Version Not Supported       H.225 ReleaseComplete
                                   (reason=invalidRevision)
  600  Busy Everywhere             H.225 ReleaseComplete
                                   (reason=adaptiveBusy)
  603  Decline                     H.225 ReleaseComplete
                                   (reason=destinationRejection)
  604  Does not exist anywhere     H.225 ReleaseComplete
                                   (reason=unreachableDestination)
  606  Not Acceptable              H.225 ReleaseComplete
                                   (reason=undefinedReason)
  INFO                             H.245 UserInputIndication
  BYE                              H.245 EndSessionCommand
                                   (H.225 ReleaseComplete message
                                    needs to be sent to close the Call
                                    Signaling Channel, if it is open)

  H.323 Message                    SIP Message
  -------------                    -----------
  H.245 sendTerminalCapabilitySet  OPTIONS
  H.245 EndSessionCommand          BYE
  H.225 Release Complete           CANCEL or BYE(if call is connected)
  RAS DRQ                          CANCEL or BYE(if call is connected)

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  Table 1: One to one mapping of SIP-H.323 messages

In most of the cases, the error messages from SIP side like 4xx, 5xx
and 6xx will be mapped to H.225 Release Complete message. The
ReleaseCompleteReason will describe the type of error on the SIP side.
Some of the error messages on one side may not always map to a
corresponding error message on the other side.

The mapping of Release Complete Reason in H.225 ReleaseComplete message with
SIP Response messages is:
ReleaseCompleteReason         SIP Message
---------------------         ----------------------------
noBandwidth                   480  Temporarily not available
gatekeeperResources           480  Temporarily not available
unreachableDestination        404  Not Found
destinationRejection          603  Decline
invalidRevision               505  Version Not Supported
noPermission                  401  Unauthorized
unreachableGatekeeper         503  Service Unavailable
gatewayResources              480  Temporarily not available
badFormatAddress              400  Bad Request
adaptiveBusy                  486  Busy Here
inConf                        486  Busy Here
undefinedReason               500  Server Internal Error
facilityCallDeflection        486  Busy Here
securityDenied                401  Unauthorized
calledPartyNotRegistered      404  Not Found
callerNotRegistered           401  Unauthorized


If IWF has been registered with GK, the mapping of H.225 Admission Reject,
Location Reject and Disengage Reject Messages with SIP Response messages is:

AdmissionRejectReason          SIP Message
---------------------         ----------------------------
CalledPartyNotRegistered       404  Not Found
InvalidPermission              401  Unauthorized
RequestDenied                  503  Service Unavailable
UndefinedReason                500  Server Internal Error
CallerNotRegistered            401  Unauthorized
routeCallToGatekeeper(*)       305   Use Proxy
invalidEndpointIdentifier      500  Server Internal Error
resourceUnavailable            503  Service Unavailable
securityDenial                 401  Unauthorized
qosControlNotSupported         501  Not Implemented
incompleteAddress              484 Address incomplete
routeCallToSCN (*)             302  Moved Temporarily
aliasesInconsistent            485  Ambiguous

LocationRejectReason           SIP Message
---------------------         ----------------------------
NotRegistered                  401  Unauthorized
InvalidPermission              401  Unauthorized
RequestDenied                  503  Service Unavailable
UndefinedReason                500  Server Internal Error

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SecurityDenial                 401  Unauthorized
routeCallToSCN(*)              302  Moved Temporarily
aliasesInconsistent            485  Ambiguous

DisengageRejectReason          SIP Message
---------------------         ----------------------------
NotRegistered                  401  Unauthorized
RequestToDropOther             401  Unauthorized
SecurityDenial                 401  Unauthorized


Mapping of 200 OK:
----------------------

In Response of INVITE          H.225 Connect
In Response of BYE             -
In Response of OPTIONS         -/Terminal Capability Set

ACK message on SIP side may be sent as a result of OLC ACK or it may be
simply sent in response of 200 OK response  of an INVITE response. However,
this mapping depends on the particular pattern of the call flow.

OPTIONS message on SIP side if requested with Accept header of
'application/sdp'  should be mapped to 'H.245 Send Terminal Capability Set'
message. The response from H.323 network in form TCS messages should be
acknowledged with TCS Ack messages and the TCS messages should be mapped to a
200 OK message to SIP networks. The reverse is true when receiving H.245 Send
Terminal Capability Set message from H.323 side.

H.225 Facility message may be used for carrying the H.245 tunnelled messages.

As call Forwarding and Call Queued is not supported in the present phase of
IWF specifications, following handling should be done on receipt of these
messages.

181 Call is Being Forwarded         501 Not Implemented
                                      H.225 Release Complete
                                      (reason=undefinedReason)
182 Queued                          501 Not Implemented
                                      H.225 Release Complete
                                      (reason=undefinedReason)



8.3. Call Sequence Mapping

Some of the messages from either SIP side or H.323 side invokes a
fixed call sequence (series of  messages)  i.e. exchange of more than
one messages on other side. These call sequences are given below:

  SIP Message                        H.323 Message Sequence
  -----------                        ----------------------
  BYE                                H.245 End Session Command
                                     H.225 Release Complete
                                     RAS DRQ

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For a outgoing call, if 200 OK has not been received, the H.245 End Session
Command or H.225 Release Complete will be mapped to Cancel.

  SIP Message                        H.323 Message Sequence
  -----------                        ----------------------
  CANCEL                             H.245 End Session Command(if open)
                                     H.225 Release Complete
                                     RAS DRQ

  H.323 Message                      SIP Message Sequence
  -------------                      --------------------
  DRQ                                4XX
                                     BYE or CANCEL

8.4. Message Parameters Mapping
This section contains the mapping of every possible parameter of all
mandatory messages of H.323 and SIP.

Details will be added in the next release of the draft.


8.5. Audio/Video Formats Mapping

A subset of IANA-registered formats and corresponding H.323-supported
capabilities are listed in Table 2.

Payload  IANA       H.323 Codec   Audio/video    clock rate    channels
Type    Encoding    Name           (A/V)          (Hz)          (audio)
____________________________________________________________________
0         PCMU        g711Ulaw64k     A              8000          1
?         ?           g711Ulaw56k     A              8000          1
2         G726-32     ?               A              8000          1
3         GSM         gsmFullRate     A              8000          1
Dynamic   GSM-HR      gsmHalfRate     A              8000          1
Dynamic   GSM-EFR     gsmEnhFullRate  A              8000          1
4         G723        g7321           A              8000          1
8         PCMA        g711Alaw64k     A              8000          1
?         ?           g711Alaw56k     A              8000          1
9         G722        g722-64k        A              8000          1
?         ?           g722-56k        A              8000          1
?         ?           g722-48k        A              8000          1
15        G728        g728            A              8000          1
18        G729        g729            A              8000          1
dyn       ?           g729AnnexA      A              8000          1
?                     g729wAnnexB     A
?                     g729AwB         A
?                     g729AnnexC      A
?                     g729Extensions  A
31        H261        h261VideoCap    V              90000
34        H263        h263VideoCap    V              90000
dyn       H263-1998   ?               V              90000


Table 2: IANA-ITU Codec mapping


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Note: H.323 only supports a clock rate of  8000 Hz; other values cannot
be mapped to H.323.

SDP attribute "ptime" gives the maximum length of time in milliseconds
represented by media in a  packet. This MAY be used for defining the
maximum packet length.

A fmtp SDP attribute for silence suppression SHOULD be defined if
silence suppression is on.

Another possible fmtp attribute MAY be the list of annexes which are
supported. This MAY be useful in translating g729AnnexB,
g729AnnexAwAnnexB, g7231AnnexC and so on to SDP.

The Video MPI (Mean Picture Interval) SHOULD mapped to the SDP
attribute  "framerate" as follows:
   mpi = 30 / framerate
   It is assumed that 29.97 Hz is rounded to 30 Hz when calculating the
framerate. So MPI of 1 become framerate 30.0, similarly MPI of 2  becomes
framerate 15. However, the IWF shall do proper rounding error correction on
the incoming side. So framerate of 29.97 should also map to MPI of 1. Note
that in SDP any possible value for framerate is allowed, but in H.323 only
multiples  of 1/29.97 are allowed. The IWF should convert the framerate to
the next lower value allowed in H.323. For example, a framerate of 12.3
frames per second in SDP is converted to an MPI value of 3 which is
equivalent to 10 frames per second.


9. Basic Message Handling

9.1. Handling of H.323 Signaling Messages

a) Calls from H.323 network directed towards IWF MAY contain the
signaling address of IWF in the destination address and the SIP address
in remote extension address of Setup message. In these cases, remote
extension address will be used to route the call else destination alias
address will be resolved to the corresponding IP address or SIP Server
address.

b) Call from H.323 network directed towards IWF MAY contain the
destination address, terminal capabilities and channel information in
different messages. This information SHALL be combined and mapped to
create the SDP information of INVITE or ACK.

9.1.1  RAS Messages

IWF is an H.323 Gateway in functionality. It can receive or send any message
which can be received or sent by an H.323 Gateway [5].

a)IWF sends RAS Messages
  GRQ -  This message is used in H.323 network to discover the H.323 GK [5].

  RRQ - This message is used in H.323 network to register with H.323 GK.


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  URQ - This message is used in H.323 network to unregister with H.323 GK.

  UCF -  This message is used in H.323 network in response of Unregister
request from H.323 GK [5].

  URJ - This message is used in H.323 network in response of Unregister
request from H.323 GK [5].

  ARQ -  This message is used in H.323 network, when  IWF receives an INVITE
message from SIP network.

  BRQ - This message is used in H.323 network [5].

  BCF   This message is used in H.323 network [5].

  BRJ   This message is used in H.323 network [5].

  IRR   This message is used in H.323 network [5].

  DRQ   This message is used in H.323 network, when IWF receives a BYE/CANCEL
or other SIP error response.

  DCF   This message is used in H.323 network [5].

  DRJ   This message is used in H.323 network [5].

  LRQ   This message is used in H.323 network [5], when IWF receives an
INVITE message and IWF is not registered with H.323 GK

  NSM   This message is used in H.323 network [5].

  XRS   This message is used in H.323 network [5].

  RIP   This message is used in H.323 network [5].

  RAI   This message is used in H.323 network [5].

b) IWF receives RAS Messages

  GCF    This message is used in H.323 network [5].

  GRJ    This message is used in H.323 network [5].

  RCF    This message is used in H.323 network as a response for register
with H.323 GK.


  RRJ    This message is used in H.323 network as a response for register
with H.323 GK.

  UCF   This message is used in H.323 network as a response for unregister
with H.323 GK.



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  URJ   This message is used in H.323 network as a response for unregister
with H.323 GK.

  ACF   This message is used in H.323 network as a response for admission
request with H.323 GK.

  ARJ   This message is used in H.323 network as a response for admission
request with H.323 GK.

  BRQ   This message is used in H.323 network [5].

  BCF  This message is used in H.323 network [5].

  BRJ   This message is used in H.323 network [5].

  IRQ   This message is used in H.323 network [5].

  IACK   This message is used in H.323 network [5].

  INAK   This message is used in H.323 network [5].

  DRQ    If the call is active, close it. Send RAS DCF (disengage confirm)
and Release Complete to H.323 entity. The corresponding BYE, CANCEL, 4xx, 5xx
or 6xx message may also be sent to the SIP side of the network.

  DCF   This message is used in H.323 network [5].

  DRJ  This message is used in H.323 network [5].

  LCF  -Send SETUP to the H.323 network for establishing the call.

  LRJ - Send a SIP error response corresponding to LocationRejectReason.

  NSM   This message is used in H.323 network [5].

  XRS   This message is used in H.323 network [5].

  RIP   This message is used in H.323 network [5].

  RAC   This message is used in H.323 network [5].




9.1.2 Q.931 Messages

   Setup
        The IWF generates an ARQ/ACF sequence if required here as per H.323
standard. However, that is local to the H.323 stack and does not affect
translation.
   If fastStart is present, convert it to H.323 capability set, else
build some default H.323 capability set. The IWF SHALL send a Q.931
CallProceeding message immediately on receiving a Call Setup message


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from H.323 entity. The IWF then sends an INVITE, where the SIP To
header field is derived from the Q.931 destinationAliasAddress and/or
destCallSignalAddress. If destinationAddress is the IWF itself, then
use remoteExtensionAddress. The From SIP header field is derived from
sourceAliasAddress and/or srcCallSignalAddress. The session description
is constructed from the H.323 capability set.If the IWF receives a 2xx
response for the INVITE, it updates the SIP capability set using the
session description in the response body. It then sends a Q.931 Connect
message to the H.323 entity.Then, the IWF sends an ACK request to the
SIP entity. Then, it sends an H.245 TCS to the H.323 entity using the
SIP capability set. It then completes the opening of channels in both
the directions.

   Call Proceeding
         This message is used in H.323 network [5]. If the IWF receives any
other 1xx SIP response, it sends a Q.931  CallProceeding message to H.323,
but only if not already sent for this call.


   Alerting
         If the IWF receives a 180 Alerting SIP response, send a Q.931
Alerting message to the H.323 entity. An Alerting message can be sent
on the receipt of 183 Progress SIP response.

On receipt of an Alerting message from H.323 entity, a 180 Alerting should be
sent to SIP entity.


   Connect
        It sends a Q.931 Connect message to H.323 entity on the receipt of
200 OK response of a INVITE messge from SIP entity and vice versa.

   Release Complete
        If no response is received or a failure response, the IWF sends a
Q.931 ReleaseComplete message to the H.323 entity.

If the IWF receives a Q.931 ReleaseComplete, the H.323 side of the
call is closed. The IWF sends a BYE to the SIP entity if the call has
been established. A SIP error response should be generated for corresponding
ReleaseCompleteReason in other cases.

   Facility
         It is used in H.323 network for carrying various service specific
informations[5].



9.1.3 H.245 Messagers

   (a) Master-slave determination messages
    After opening the H.245 Channel, IWF completes the Master-slave
determination with the H.323 entity. This is for internal use of IWF only.



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   (b) Terminal Capability Messages
    In order to establish the logical channels for a call in Non-Fast Connect
mode, IWF sends the  Terminal Capability message to H.323 entity with the
media capabilities of the SIP entity. The SIP messages contains the media
capability in the SDP format.

    If it receives a Terminal Capability Set (TCS), it updates the H.323
capability set and calculates the maximal intersection of the H.323 and SIP
capability sets, called C. From C, the IWF derives a suitable operating mode
(say M). For each element in M in the direction from SIP to H.323,send a
 H.245 Open Logical Channel (OLC) to the H.323 entity.  The OLC messages use
the transport addresses of the SIP capability set, derived from the session
description in the 2xx response body.

    When an IWF receives a TCS message , it will be mapped to the "m=" line
of SDP with each line containing only one payload type.

   (c) Logical Channel signaling messages

   If the IWF receives an OLC and the logical channel is present in the
operating mode from H.323 to SIP, it responds with an OLCAck. The
OLCAck uses the transport addresses of the SIP capability set. If the
logical channel is not present in the operating mode, the IWF sends an
OLCReject. Once the IWF has received OLCAck or OLCRej for all the
requests, update the operating mode.  Then, the IWF sends a re-INVITE.
The session description is formed using the new operating mode if it is
different from what was sent in the first INVITE message and the
transport addresses received in OLCAcks. The IWF should wait for a 2xx
response from the SIP entity and respond with an ACK request. If it
times out or if it fails, it should close the call.

   If there is a change in SDP description for a Logical Channel, IWF issues
a Close Logical channel, Request Channel Close, messages. IWF also supports
their responses.


   (d) Mode Request or Change in Logical Channels
   Update operating modes, Send re-INVITE to SIP entity. If that fails then
reject the Mode Request or Open Logical Channel request.

   (e)  EndSession Command
   If the IWF receives a H.245 EndSession, it closes the H.245 call.
Send H.245 EndSession and Q.931 ReleaseComplete to H.323 entity and
send RAS DRQ to gatekeeper if it admitted the call.

   If the IWF receives a BYE or SIP error response for a call with H.245
session, it sends an H.245 EndSession commands to H.323 entity.

   (f) When an IWF receives a UserInputIndication message, it MAY  be
sending the DTMF to SIP using SIP INFO method. Only the alphanumeric
method of userinputIndication is considered for this release of the
draft. Other mapping between the INFO msg body and the signal type of
userinput is left for further study.


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    IWF MAY use a proprietary non-INFO method based solution that
interworks with H.245 UserInputIndication.

    IWF May Use a proprietary INFO method based solution that
interworks with H.245 UserInputIndication.

    IWF May Use a proprietary/standard non-INFO method based solution
that could backhaul in-band DTMF signaling to the IWF and which would
interwork with H.245 UserInputIndication

    (g) Send Terminal Capability Set

     IWF issues this command corresponding to SIP OPTIONS messages to
determine the capability of H.323 entity. On receipt of Send Capability Set
command from H.323 entity, IWF sends an OPTION command to SIP entity for
determining its media capability.



9.2. Handling of SIP Signaling Messages

   (a) Receiving INVITE for a New Call

   The IWF SHALL respond with a 100 (Trying) response to the SIP entity
immediately after receiving the INVITE request. It stores the SDP
information as the terminal's SIP capability and convert the SIP UA
capabilities  to  create the H.245 TCS.

   If the IWF is registered with a gatekeeper, send a RAS ARQ message
to the gatekeeper, where the destinationInfo and destCallSignalAddress is
derived from the To SIP header, the sourceInfo is derived from the From SIP
header field and sourceCallSignalAddress is the call signaling
address of the IWF itself.  The gatekeeper assigns an endpointIdentifier
during registration.  That value of endpointIdentifier is used in the
endpointIdentifier field of the ARQ
message.

Next, the IWF should receive either a RAS ACF or ARJ message. If an ACF
message is received, establish an Q.931 channel as described below. If
an ARJ message is received, the behavior depends on the reason
parameter as follows:

        CalledPartyNotRegistered: The IWF responds with 404 (Not
             Found).
        callerNotRegistered: The IWF MAY register, with a RAS RRQ
             message, the SIP address with the gatekeeper and then
             retransmit the RAS request, with the endpointIdentifier
             returned in RCF. Alternatively, it MAY send a 400 (Caller
             not registered) response to the SIP entity.
        incompleteAddress:  Send 484 (Address Incomplete) response to
             SIP entity.
        Other reasons: Send 400 (Bad Request) response to
             SIP entity for H.323 translation failure.


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If the IWF times out waiting for an ARQ response, it sends a SIP 504
(Gateway time-out) response.

If the IWF is not registered with a gatekeeper and it is able to
resolve the SIP address to a H.323 address or if the IWF is registered
and has received an ACF for the registration request from the
gatekeeper, the IWF sends a Q.931 SETUP message to the H.323 entity,
where the sourceAddress is derived from the SIP From header,the
destinationAddress is derived from the SIP To header or from the RAS
ACF response, destCallSignalAddress is derived from the RAS ACF
response or from the To SIP header. The remoteExtensionAddress is
copied from RAS ACF if present or extracted from To SIP header if
possible.  The sourceCallSignalAddress is the call signaling transport
address of the IWF. fastStart PDUs are mapped from the session
description in the INVITE message body.

Each SDP payload type entry is converted to an OLC message. All the
payload types on the SDP same media description line have the same
session id in the OLC messages. This identifies them as belonging to
the same group and the receiving H.323 entity will select one of these.
(TBD: needs more description)

If the IWF receives a Q.931 CallProceeding message, send a 100 (Trying)
response to the SIP entity, if not already sent.  If fastStart PDUs are
present, store them.

If the IWF receives a Q.931 Alerting message, send a 180 (Alerting)
response to the SIP entity, indicating that the final destination is
ringing. If fastStart PDUs are present, store them.

If the IWF receives a Q.931 Connect message, the behavior depends on
whether a FastStart indication is present. If a FastStart indication is
present, the IWF maps the received OLCs to the SDP payload types

contained in the original INVITE request. Format a new SDP packet with
more constrained media description and correct media transport address
of the H.323 entity.  Now each media description line will contain a
single payload type, depending on which OLC PDUs are present. The
operating mode and H.323 capability set are set to this reduced set of
payloads.

The SDP message is sent in a 200 (OK) response. The IWF then waits for
the ACK request from the SIP entity. If the IWF times out, it declares
the call closed and terminates the H.323 call. Once an ACK has been
received, the IWF may proceed with other H.245 signaling (CESE, RTDSE
and so on).

If the H.323 entity does not support FastStart, the IWF proceeds with
H.245 signaling as described below. First, it sends a TCS to the the
H.323 entity and uses the stored SIP capability set to generate the
H.245 capabilities.



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If the IWF receives an H.245 TCS message, it updates the H.323
capability set and calculates maximal intersection of H.323 and SIP
capability sets (call this C). Derive a suitable operating mode from C
(say, M). For each element in M (for the data from the SIP UA to the
H.323 terminal), send an H.245 OLC message to the H.323 entity. Use the
transport address of the SIP capability set, derived from the SDP
received in the original INVITE message.

   If the IWF receives an OLC message and the logical channel is
present  in the operating mode from the H.323 terminal to the SIP UA,
the IWF sends an OLCAck to the H.323 terminal. The OLCAck contains the
transport address from the SIP capability set, again derived from the
SDP in the INVITE message body. If the logical channel is not present
in that operating mode, the IWF sends an OLCReject. Once the IWF has
received an OLCAck or OLCRej for all outstanding OLC requests, it
updates the operating mode and sends a 200 (OK) response to the SIP
entity. The session description in that response is formed using the
new operating mode and the transport addresses received in the H.245
OLCAcks. The IWF should wait for the ACK request from the SIP entity.

If the IWF times out, it should close the H.323 call. This concludes
the description of the non-FastStart handling.


If, at any time, the IWF receives a Q.931 ReleaseComplete message, a
H.323 call could not be established. The IWF sends a 400 (Bad Request)
for the request failure with reason phrase "H.323 call failed".

If the Q.931 SETUP times out, the IWF sends a 504 (Gateway time-out)
response.

If the SIP address is not resolved to an H.323 address, send a 501 (Not
Implemented) response to SIP entity.

   (b) Sending INVITE for a new call

      On receipt of SETUP message from H.323 side, IWF sends an INVITE
message to SIP entity.

   (c) INVITE for an Existing Call

        o Update the SIP capability set.

        o Recalculate the operating mode, minimizing changes. An H.245
          Mode Request message is sent if the operating mode has
          changed.  If the Mode Request fails, either close the media
          channel or the call.

   (d) BYE Request

      The IWF sends an H.245 Endsession to the H.323 entity. Upon
   receipt of a response or on timeout, the IWF sends a Q.931
   ReleaseComplete to H.323 entity. If the call was admitted by a GK,
   send a RAS DRQ (Disengage Request) message to the GK.

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   (e) OPTIONS Request

   TBD: how do we query H.323 capabilities without establishing the
   Call because there is no standard mechanism in H.323?

   The IWF sends a RAS RRQ message to the H.323 GK, where the
   callSignalAddress is the address of the IWF, the terminalType is set
   to "gateway" and the terminalAlias is mapped from the To header of
   the REGISTER request.

   The IWF stores the SIP Contact header field. A "200 OK" SIP status
   response is sent after receiving a RAS RCF message.

10. Interworking Call Scenarios for Different Configurations


In cases where SIP Server or H.323 GK coexists with IWF, they will
still be treated as separate logical entities. This is because seperate
instances of H.323 stack will be running for H.323 GK and IWF.
Similarly, there will be seperate instances of SIP stack running at
both IWF and SIP server. All call flow diagrams will therefore shows
IWF as a seperate logical entity and SHALL always include call
messaging between IWF and H.323 GK/SIP Server (if they exists).

10.1. Registration and Address Resolution Services

10.1.1. Registration

In H.323, registration is the process by which an endpoint joins a
Zone,and informs the Gatekeeper of its Transport Address and alias
addresses.As a part of their configuration process, all endpoints shall
register with the Gatekeeper identified through the discovery process.
Registration shall occur before any calls are attempted and may occur
periodically as necessary (for example, at endpoint power-up or before
registration timeout).

An endpoint shall send a Registration Request (RRQ) message to a
Gatekeeper. This is sent to the Gatekeeper's RAS Channel Transport
Address. The endpoint has the Network Address of the Gatekeeper from
the Gatekeeper discovery process and uses the well-known RAS Channel
TSAP Identifier. The Gatekeeper shall respond with either a
Registration Confirmation (RCF) or a Registration Reject (RRJ) message.

In SIP, the REGISTER request allows a client to let a proxy or redirect
server know at which address(es) it can be reached. A client MAY also
use it to install call handling features at the server. A client uses
the REGISTER method to register the address listed in the To header
field with a SIP server.

The Register request MAY contain a Contact header field; future non-
REGISTER requests for the URI given in the To header field SHOULD be
directed to the address(es) given in the Contact header.

A user agent MAY register with a local server on startup by sending a
REGISTER request to the well-known "all SIP servers" multicast address

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"sip.mcast.net" (224.0.1.75). This request SHOULD be scoped to ensure
it is not forwarded beyond the boundaries of the administrative system.
The unicast method can also be used for registration if address of the
registration is known.

The SIP server registers the user in its contact database and returns a
response 200 OK to the user's SIP client. The response includes the
user's current contact list in Contact headers.

During initialization, the IWF MAY registers its own alias address
(e.g., gw1) with its local H.323 gatekeepers, so that anybody from the
H.323 cloud can reach SIP endpoints by directly connecting to the alias
address of the IWF and by providing a SIP address in the remote
extension address of the SETUP message of H.323.

10.1.2. Address Resolution

In H.323, an endpoint or Gatekeeper which has an alias address for an
endpoint and would like to determine its contact information may issue
a Location Request (LRQ) message. This message may be sent to a
specific Gatekeeper's RAS Channel TSAP Identifier, or may be multicast
to the Gatekeeper's well-known Discovery Multicast Address. The
Gatekeeper with which the requested endpoint is registered, shall
respond with the Location Confirmation (LCF) message containing the
contact information of the endpoint or the endpoint's Gatekeeper.
Contact information shall include the Call Signalling Channel and RAS
Channel addresses to be used to reach the endpoint and optionally
additional destination information which can  provide dialling
information and extension information concerning the requested
endpoint.

All Gatekeepers with which the requested endpoint is not registered,
shall return Location Reject (LRJ) if they received the LRQ on the RAS
Channel. Any Gatekeeper with which the requested endpoint is not
registered, shall not respond to the LRQ, if it received the LRQ on the
Discovery Multicast address.

In SIP, the REGISTRATION method is used to register the address(es) of
the user in the SIP server (register, redirect, proxy) and the SIP
server registers the address(es) in its contact database. A SIP

register/redirect/proxy server returns the list to the client as
Contact headers. A SIP register/redirect/proxy server can return the
address(es) where the user can be contacted.

The OPTION method of SIP can also be used to resolve the addresses. For
example, the SIP server may be queried for knowing its capabilities
using the OPTION method. If the server that believes it can contact the
user, such as a user agent where the user is logged in and has been
recently active, MAY respond to this request with a capability set
along with the address(es) where the user can be contacted.




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10.1.3. Registration and Address Resolution Scenarios

An RRQ contains an endpointType, which will, in the IWF case, contain a
GatewayInfo SEQUENCE that contains the SupportedProtocols.  In H.323v2,
each of these SupportedProtocols contains a SEQUENCE OF dial prefixes.
This is where the number ranges are specified by way of prefixes. Also,
most GKs support some form of static configuration to do the same  job
by less elegant means if either IWF or GK is version 1 or doesn't
support this feature for other reasons. This method of dial prefixes
and number range will help in address resolution in cases when the SIP
and H.323 domain are well defined with a dialing plan.

* Registration of the IWF as SIP User Agent TRIP may be used, but left for
further study.


10.1.4. Advertisement of SIP Support by H.323 Gateways

As the Session Initiation Protocol (SIP) gains wider acceptance, it is
important to build gateways that provide an interworking function
between the two protocols. It is our recommendation that we add SIP to
the list of supported protocols advertised by an H.323 gateway to its
gatekeeper.

The semantics of existing desired/supported protocol information
elements were not appropriate for an H.323 gateway to indicate SIP
support to an H.323 gatekeeper.  Currently, the best practice for a
H.323 gateway (supporting SIP) implementation is to use the h323
information element in the SupportedProtocols choice for this purpose.

The use of such a field means that this H.323 gateway (supporting SIP)
is a pure H.323 proxy, which is not semantically correct.

Appendix B gives the  modified ASN.1 to show the additions to the H.225
for the support of SIP protocol.



10.2. Call Flows for Basic Configuration

H.323 EP  ---- IWF ---- SIP EP
a)  Simple Call from H.323 terminal to SIP terminal.

   H.323 EP                       IWF                     SIP EP
     User A                                                User B
(164.164.28.101)            (164.164.28.121)          (164.164.28.141)
   RTP  = 2326                                       RTP  = 4346
   RTCP = 2327                                       RTCP = 4347
       |Setup(vipin@iwf.sip.com) F1|                           |
       |-------------------------->| INVITE F2                 |
       | Call Proc F3              |-------------------------->|
       |<--------------------------| c=IN IP4 164.164.28.121   |
       |                           | m=audio 0 RTP/AVP 0       |
       |                           | a=rtpmap:0 PCMU/8000      |

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       |                           |                           |
       |                           |        100 Trying F4      |
       |                           |<--------------------------|

       |                           |        180 Ringing F5     |
       |         Alerting F6       |<--------------------------|
       |<--------------------------|          200 OK F7        |
       |         Connect F8        |<--------------------------|
       |<--------------------------|  c=IN IP4 164.164.28.141  |
       |                           |  m=audio 4346 RTP/AVP 0   |
       |                           |  a=rtpmap:0 PCMU/8000     |
       |          TCS   F10        |          ACK  F9          |
       |-------------------------->|-------------------------->|
       |        TCS Ack F11        |                           |
       |<--------------------------|                           |
       |     TCS           F12     |                           |
       |<--------------------------|                           |
       |         TCS Ack F13       |                           |
       |-------------------------->|                           |

       |           MSD F14         |                           |
       |-------------------------->|                           |
       |          MSD F14A         |                           |
       |<--------------------------|                           |
       |         MSD Ack F15       |                           |
       |<--------------------------|                           |
       |         MSD Ack F16       |                           |
       |-------------------------->|                           |
       |OLC(RTCP=2327,g711Ulaw) F17|                           |
       |-------------------------->|                           |
       | OLC Ack(RTP=4326, F18     |                           |
       |<--------------------------|                           |
       |     164.164.28.141)       |                           |
       |                           |                           |
       |OLC(RTCP=4347,g711Ulaw) F19|                           |
       |<--------------------------|                           |
       |                           |                           |
       | OLC Ack(RTP=2326, F20     |                           |
       |-------------------------->|        INVITE F21         |
       |    164.164.28.101         |-------------------------->|
       |                           | c=IN IP4 164.164.28.101   |
       |                           | m=audio 2326 RTP/AVP 0    |
       |                           | a=rtpmap:0 PCMU/8000      |
       |                           |                           |
       |                           |          200 OK F22       |
       |                           |<--------------------------|
       |                           |  c=IN IP4 164.164.28.141  |
       |                           |  m=audio 4346 RTP/AVP 0   |
       |                           |  a=rtpmap:0 PCMU/8000     |
       |                           |                           |
       |                           |          ACK  F23         |
       |                           |-------------------------->|



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       |                          RTCP                         |
  2327 |<=====================================================>| 4347
       |                          RTP                          |
  2326 |<=====================================================>| 4346


This call flow shows the use of a re-INVITE (F20) by the IWF to update
the SIP end point SDP.  The initial INVITE (F2) contains "dummy" SDP of
 the IWF, since the SDP of the H.323 EP is not yet known.


The details of call flow messages are given in Appendix C.1.

b) Call from H.323 terminal to SIP terminal using H.245 tunneling.

      H.323                                                   SIP
       EP                        IWF                          EP
     User A                                                 UserB
       | Setup(tunn= true,MSD,TCS) F1                         |
       |------------------------->|          INVITE F2        |
       |                          |-------------------------->|
       |                          |        180 Ringing F3     |
       |       Alerting    F4     |<--------------------------|
       |<-------------------------|                           |
       |                          |         200 OK F5         |
       | Connect(MSD Ack,TCS  F6  |<--------------------------|
       |<-------------------------|                           |
       |  TCS Ack)                |                           |
       |                          |                           |
       | Facility(TCS Ack,OLC  F7 |                           |
       |------------------------->|                           |
       |   MSD Ack)               |                           |
       |                          |                           |
       | Facility(OLC Ack,OLC) F8 |                           |
       |<-------------------------|                           |
       |  Facility(OLC Ack) F9    |                           |
       |------------------------->|                           |
       |                          |                           |
       |                          |                           |
       |                          |           ACK  F10        |
       |                          |-------------------------->|
       |                         RTP                          |
       |<====================================================>|


This call flow shows the delayed SDP approach, where the initial INVITE
(F2) does not contain SDP, but the ACK (F10) does.  In this call flow,
it is possible that the SIP end point will time out and retransmit the

200 OK (F5) response, thinking that it had been lost. For simplicity,
it is not shown here.

The details of call flow messages are given in Appendix C.2.

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c) Call from H.323 terminal to SIP terminal using early H.245.


      H.323                                                   SIP
       EP                        IWF                          EP
       | Setup(H245 Address)      |                           |
       |------------------------->|          INVITE           |
       |                          |-------------------------->|
       |   H245 Start here        |                           |
       |<------------------------>|      180 Ringing          |
       |       Alerting           |<--------------------------|
       |<-------------------------|          200 OK           |
       |       Connect            |<--------------------------|
       |<-------------------------|                           |
       |  H245 Ends upto this     |                           |
       |<------------------------>|         ACK               |
       |                          |-------------------------->|
       |                         RTP                          |
       |<====================================================>|


This call flow and message exchanges are very much similar to Section
(10.2 a) except that IWF in this case gets the H.245 address of H.323
EP in Setup message. Using this H.245 address and TSAP identifier, IWF
opens an H.245 channel with H.323 EP prior to completing Q.931. In this
case, all the normal H.245 messages will be exchanged on the seperate
H.245 channel but it will be done simultaneously along with Q.931. The
ACK on SIP side will be sent only after completing the H.245 message
exchange on the H.323 side.

d) Call from H.323 terminal to SIP terminal using fast connect
procedure.

     H.323                                                   SIP
       EP                        IWF                          EP

       | Setup(fastStart=true,OLC)|                           |
       |------------------------->|          INVITE     F2    |
       |                   F1     |-------------------------->|
       |                          |       180 Ringing   F3    |
       |      Alerting     F4     |<--------------------------|
       |<-------------------------|          200 OK     F5    |
       | Connect(fastStart=true,  |<--------------------------|
       |<-------------------------|                           |
       |     OLC)          F6     |           ACK       F7    |
       |                          |-------------------------->|
       |                         RTP                          |
       |<====================================================>|

This call flow has the most perfect matching of H.323 message
and parameters with SIP message and parameters. Setup from
H.323 endpoint will contain the media channel information for forward
and reverse channels. This will help in mapping the complete channel
information to SDP of SIP INVITE. Similarly, SDP of 200 OK response

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from SIP side can be easily mapped to open the channels on H.323 side.

This call flow will give the immediate availability of media channels
from both sides after H.323 Connect and SIP Ack.

The details of call flow messages are given in Appendix C.3.

e) Call from H.323 terminal to SIP terminal using overlapped sending.


     H.323                                                   SIP
       EP                        IWF                          EP
     User A                                                 User B
       | Setup(canOverlapSend= F1 |                           |
       |------------------------->|                           |
       | true, Incomplete Add.)   |                           |
       |                          |                           |
       |       Setup Ack F2       |                           |
       |<-------------------------|        INVITE F3          |
       |                          |-------------------------->|
       |                          |    484 Address Inc. F4    |
       |                          |<--------------------------|

       |                          |           ACK F5          |
       |Information(additional F6 |-------------------------->|
       |------------------------->|                           |
       | address)                 |       INVITE F7           |
       |                          |-------------------------->|
       |                          |    180 Ringing F8         |
       |       Alerting F9        |<--------------------------|
       |<-------------------------|     200 OK F10            |
       |        Connect F11       |<--------------------------|
       |<-------------------------|                           |
       |          H245 F12        |                           |
       |<------------------------>|         ACK  F13          |
       |                          |-------------------------->|
       |                         RTP                          |
       |<====================================================>|

This call flow shows overlapped dialing.  On the SIP side, the Call-ID
remains the same throughout the flow.

The SETUP message contains either:

a) no called number information; or
b) incomplete called number information; or
c) called number information which the network cannot determine to be
complete.

On receipt of such a SETUP message, the network starts timer T302 (as
specified in Q.931), sends a SETUP ACKNOWLEDGE message to the user, and
enters the overlap sending state. In case a), the network will return
dial tone, if required by the tone option. In this case further address
information will be available in the SETUP ACKNOWLEDGE message.

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When the SETUP ACKNOWLEDGE message is received, the user enters the
overlap sending state and optionally starts timer T304 (the value of
timer T304 is specified in Q.931 [12]). After receiving the SETUP
ACKNOWLEDGE message, the user sends the remainder of the call
information (if any) in one or more INFORMATION messages.

The called party number information may be provided by the user as
follows:

a) in the called party number information element; or
b) in the keypad facility information element, exclusively.

The called party number must be sent in a unique way.


The details of call flow messages are given in Appendix C.4.

g) Call from SIP terminal to H.323 terminal using H.245 tunneling.

    User B                                                  User A
      SIP                                                   H.323
       EP                        IWF                          EP
       |   INVITE            F1   |                           |
       |------------------------->| Setup(tunn. =true,TCS,MSD)|
       |                          |-------------------------->|
       |                          |                   F2      |
       |                          |                           |
       |                          | Alerting(tunn.=true,TCSAck|
       |                          |<--------------------------|
       |      180 Ringing    F4   | MSD Ack,TCS)      F3      |
       |<-------------------------|                           |
       |                          |Facility(mess-body=empty,  |
       |                          |-------------------------->|
       |                          |TCS Ack,OLC,MSD Ack) F5    |
       |                          |                           |
       |                          |Facility(OLC Ack,OLC) F6   |
       |                          |<--------------------------|
       |                          |Facility (OLC Ack)   F7    |
       |                          |-------------------------->|
       |                          | Connect           F8      |
       |        200 OK       F9   |<--------------------------|
       |<-------------------------|                           |
       |         ACK         F10  |                           |
       |------------------------->|                           |
       |                         RTP                          |
       |<====================================================>|


The details of call flow messages are given in Appendix C.5.






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h) Call from SIP terminal to H.323 terminal using early H.245.

      SIP                                                   H.323
       EP                        IWF                          EP

       |   INVITE                 |                           |
       |------------------------->| Setup(h245 Address)       |
       |                          |-------------------------->|
       |                          | Early H245 starts here    |
       |                          |<------------------------->|
       |                          |        Alerting           |
       |        180 Ringing       |<--------------------------|
       |<-------------------------|        Connect            |
       |                          |<--------------------------|
       |                          | Early H245 ends upto this |
       |        200 OK            |<------------------------->|
       |<-------------------------|                           |
       |         ACK              |                           |
       |------------------------->|                           |
       |                         RTP                          |
       |<====================================================>|

The call flow diagram for this call is similar to call flow f)
except that in this case the H.245 channel was opened immediately
after an H.323 endpoint received the H.225 Setup message.

i) Call from SIP terminal to H.323 terminal using fast connect
procedure.


      SIP                                                   H.323
       EP                        IWF                          EP
       |   INVITE                 |                           |
       |------------------------->| Setup(fastStart=true,OLC) |
       |                          |-------------------------->|
       |                          |     Alerting              |
       |        180 Ringing       |<--------------------------|
       |<-------------------------|Connect(fastStart=true,OLC)|
       |          200 OK          |<--------------------------|
       |<-------------------------|                           |
       |           ACK            |                           |
       |------------------------->|                           |
       |                         RTP                          |
       |<====================================================>|


This call flow gives a perfect matching of call sequence and
parameters.







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j) Call from SIP terminal to H.323 terminal using overlapped
sending.

      SIP                                                   H.323
       EP                        IWF                          EP
     User B                                                 User A
       |        INVITE F1         |                           |
       |------------------------->| Setup(canOverlapSend=true) F2
       |                          |-------------------------->|
       | 484 Address Incomplete F3|                           |
       |<-------------------------|                           |
       |          ACK F4          |                           |
       |------------------------->|       Setup Ack.  F5      |
       |                          |<--------------------------|
       |                          |                           |
       |         INVITE F6        |                           |
       |------------------------->| Information(Additional F7 |
       |                          |-------------------------->|
       |                          |  Address)                 |
       |                          |                           |
       |                          |        Alerting F8        |
       |      180 Ringing F9      |<--------------------------|
       |<-------------------------|        Connect F10        |
       |                          |<--------------------------|
       |                          |         H245 F11          |
       |        200 OK F12        |<------------------------->|
       |<-------------------------|                           |
       |          ACK F13         |                           |
       |------------------------->|                           |
       |                         RTP                          |
       |<====================================================>|

This call flow shows overlapped dialing.  On the SIP side, the Call-ID
remains the same throughout the flow.

The details of  call flow messages are given in Appendix C.6.


10.3 Calls using both H.323 GK and SIP Server

H.323 EP ---- H.323 GK ---- IWF ---- SIP Server ---- SIP EP

Assumption:

GK routes the call up to Q.931 signaling only. This section only
gives the details of call sequence. Message details are similar
and can be derived from the details of Section 10.2.


a) Simple Call from H.323 terminal to SIP terminal.




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  (i) With SIP Proxy

      H.323        H.323                        SIP           SIP
       EP           GK            IWF          Proxy           EP
       |     ARQ     |             |             |             |
       |------------>|             |             |             |
       |     ACF     |             |             |             |
       |<------------|             |             |             |
       |    Setup    |             |             |             |
       |------------>|      Setup  |             |             |
       |             |------------>|             |             |
       |             |       ARQ   |             |             |
       |             |<------------|             |             |
       |             |       ACF   |             |             |
       |             |------------>|    INVITE   |             |
       |             |             |------------>|   INVITE    |
       |             |             |             |------------>|
       |             |             |             | 180 Ringing |
       |             |             | 180 Ringing |<------------|
       |             |  Alerting   |<------------|             |
       |   Alerting  |<------------|             |             |
       |<------------|             |             |    200 OK   |
       |             |             |    200 OK   |<------------|
       |             |   Connect   |<------------|             |
       |   Connect   |<------------|             |             |
       |<------------|             |             |             |
       |       H.245               |             |             |

       |<------------------------->|     ACK     |             |
       |             |             |------------>|     ACK     |
       |             |             |             |------------>|
       |             |             |             |             |
       |             |          RTP              |             |
       |<=====================================================>|

  (ii) With SIP Redirect

   H.323        H.323                      SIP           SIP
    EP            GK          IWF        Redirect         EP
    |     ARQ     |            |            |              |
    |------------>|            |            |              |
    |     ACF     |            |            |              |
    |<------------|            |            |              |
    |    Setup    |            |            |              |
    |------------>|   Setup    |            |              |
    |             |----------->|            |              |
    |             |     ARQ    |            |              |
    |             |<-----------|            |              |
    |             |     ACF    |            |              |
    |             |----------->|   INVITE   |              |
    |             |            |----------->|              |
    |             |            |  302 Moved |              |
    |             |            |<-----------|              |


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    |             |            |    ACK     |              |
    |             |            |----------->|              |
    |             |            |         INVITE            |
    |             |            |-------------------------->|
    |             |            |         180 Ringing       |
    |             |   Alerting |<--------------------------|
    |   Alerting  |<-----------|                           |
    |<------------|            |         200 OK            |
    |             |   Connect  |<--------------------------|
    |    Connect  |<-----------|                           |
    |<------------|            |                           |
    |        H.245             |                           |
    |<------------------------>|          ACK              |
    |                          |-------------------------->|
    |                        RTP                           |

    |<====================================================>|


This call flow shows the message sequence in case of H.323 GK and
SIP Server. Details of messages are similar to other call flows
explained above.

b) Call from H.323 terminal to SIP terminal using H.245 tunneling.

   H.323        H.323                      SIP            SIP
    EP            GK          IWF         Proxy           EP
    |     ARQ     |            |            |              |
    |------------>|            |            |              |
    |     ACF     |            |            |              |
    |<------------|            |            |              |
    |Setup(tunn=  |            |            |              |
    |------------>|   ARQ      |            |              |
    |true,TCS,MSD)|----------->|            |              |
    |             |   ACF      |            |              |
    |             |<-----------|            |              |
    |             |Setup(tunn= |            |              |
    |             |----------->| INVITE     |              |
    |             |true,TCS,MSD|----------->|  INVITE      |
    |             |            |            |------------->|
    |             |            |            |  180 Ringing |
    |             |            |180 Ringing |<-------------|
    |             |Alerting(MSD|<-----------|              |
    |Alerting(MSD |<-----------|            |              |
    |<------------|Ack,TCS Ack,|            |    200 OK    |
    |Ack,TCS Ack, |TCS)        |   200 OK   |<-------------|
    |TCS)         |            |<-----------|              |
    |             |            |            |              |
    |Facility(OLC)|            |            |              |
    |------------>|Facility(OLC|            |              |
    |             |----------->|            |              |
    |             |            |            |              |



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    |             |Facility(OLC|            |              |
    |Facility(OLC |<-----------|            |              |
    |<------------|Ack,OLC)    |            |              |
    |Ack,OLC)     |            |            |              |

    |             |            |            |              |
    |Facility(OLC |            |            |              |
    |------------>|Facility(OLC|            |              |
    | Ack)        |----------->|            |              |
    |             | Ack)       |            |              |
    |             |            |            |              |
    |             | Connect    |            |              |
    |   Connect   |<-----------|            |              |
    |<------------|            |            |              |
    |            H245          |            |              |
    |<------------------------>|    ACK     |              |
    |             |            |----------->|     ACK      |
    |             |            |            |------------->|
    |                         RTP           |              |
    |<====================================================>|


In this call scenario, it takes too much time between "200 OK" and
"ACK". The other approach can be to send the ACK immediately and then
resend a "INVITE" after completing H.245 message exchange.

c) Call from H.323 terminal to SIP terminal using early H.245.
      H.323        H.323                        SIP           SIP
       EP           GK            IWF          Proxy           EP
       |     ARQ     |             |             |             |
       |------------>|             |             |             |
       |     ACF     |             |             |             |
       |<------------|             |             |             |
       |Setup(H245   |             |             |             |
       |------------>|   ARQ       |             |             |
       | Address)    |------------>|             |             |
       |             |    ACF      |             |             |
       |             |<------------|             |             |
       |             | Setup(H245  |             |             |
       |             |------------>|    INVITE   |             |
       |             | Address)    |------------>|   INVITE    |
       |  H245 Starts here         |             |------------>|

       |<------------------------->|             | 180 Ringing |
       |                           | 180 Ringing |<------------|
       |             |  Alerting   |<------------|    200 OK   |
       |  Alerting   |<------------|    200 OK   |<------------|
       |<------------|  Connect    |<------------|             |
       |  Connect    |<------------|             |             |
       |<------------|             |             |             |
       | H245 Ends upto this       |             |             |
       |<------------------------->|    ACK      |             |
       |             |             |------------>|     ACK     |
       |             |             |             |------------>|
       |             |            RTP            |             |
       |<====================================================>|
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d) Call from H.323 terminal to SIP terminal using fast connect
procedure.


      H.323        H.323                        SIP           SIP
       EP           GK            IWF          Proxy           EP
       |     ARQ     |             |             |             |
       |------------>|             |             |             |
       |     ACF     |             |             |             |
       |<------------|             |             |             |
       |Setup(fast   |             |             |             |
       |------------>|     ARQ     |             |             |
       |Conn,OLC)    |------------>|             |             |
       |             |     ACF     |             |             |
       |             |<------------|             |             |
       |             |Setup(fast   |             |             |
       |             |------------>|    INVITE   |             |
       |             |Conn,OLC)    |------------>|  INVITE     |
       |             |             |             |------------>|
       |             |             |             | 180 Ringing |
       |             |             | 180 Ringing |<------------|
       |             |  Alerting   |<------------|  200 OK     |
       | Alerting    |<------------|    200 OK   |<------------|
       |<------------|  Connect    |<------------|             |
       |  Connect    |<------------|             |             |

       |<------------|             |             |             |
       |            H245           |             |             |
       |<------------------------->|    ACK      |             |
       |             |             |------------>|      ACK    |
       |             |             |             |------------>|
       |             |            RTP            |             |
       |<=====================================================>|

e) Call from H.323 terminal to SIP terminal using overlapped
sending.



      H.323        H.323                        SIP           SIP
       EP           GK            IWF          Proxy           EP
       |ARQ(Incomp.  |             |             |             |
       |------------>|             |             |             |
       | Address)    |             |             |             |
       |             |             |             |             |
       |ARJ(rejectRea|             |             |             |
       |<------------|             |             |             |
       |son=Incomp.  |             |             |             |
       | Address)    |             |             |             |
       |             |             |             |             |
       |ARQ(Addition |             |             |             |
       |------------>|             |             |             |
       |al Address)  |             |             |             |
       |             |             |             |             |

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       |    ACF      |             |             |             |
       |<------------|             |             |             |
       |   Setup     |             |             |             |
       |------------>|      Setup  |             |             |
       |             |------------>|             |             |
       |             |       ARQ   |             |             |
       |             |<------------|             |             |
       |             |       ACF   |             |             |
       |             |------------>|    INVITE   |             |
       |             |             |------------>|   INVITE    |
       |             |             |             |------------>|
       |             |             |             | 180 Ringing |
       |             |             | 180 Ringing |<------------|
       |             |  Alerting   |<------------|             |
       |   Alerting  |<------------|             |             |
       |<------------|             |             |    200 OK   |
       |             |             |    200 OK   |<------------|
       |             |   Connect   |<------------|             |
       |   Connect   |<------------|             |             |
       |<------------|             |             |             |
       |       H.245               |             |             |
       |<------------------------->|     ACK     |             |
       |             |             |------------>|     ACK     |
       |             |             |             |------------>|
       |             |             |             |             |
       |             |          RTP              |             |
       |<=====================================================>|

f) Simple call from SIP terminal to H.323 terminal.

  (i)  With SIP Proxy


    SIP         SIP                         H.323           H.323
    EP         Proxy           IWF           GK             EP
    |             |             |             |             |
    |  INVITE     |             |             |             |
    |------------>|  INVITE     |             |             |
    |             |------------>|     ARQ     |             |
    |             |             |------------>|             |
    |             |             |       ACF   |             |
    |             |             |<------------|             |
    |             |             |      Setup  |             |
    |             |             |------------>|   Setup     |
    |             |             |             |------------>|
    |             |             |             |    ARQ      |
    |             |             |             |<------------|
    |             |             |             |    ACF      |
    |             |             |             |------------>|
    |             |             |             |  Alerting   |
    |             |             |  Alerting   |<------------|
    |             | 180 Ringing |<------------|             |


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    | 180 Ringing |<------------|             |             |
    |<------------|             |             |   Connect   |
    |             |             |   Connect   |<------------|
    |             |             |<------------|             |
    |             |             |            H.245          |
    |             |    200 OK   |<------------------------->|
    |   200 OK    |<------------|             |             |
    |<------------|             |             |             |
    |   ACK       |             |             |             |
    |------------>|     ACK     |             |             |
    |             |------------>|             |             |
    |             |                RTP        |             |
    |<=====================================================>|


   (ii) With SIP Redirect

   SIP            SIP                       H.323       H.323
    EP         Redirect        IWF            GK           EP
    |  INVITE     |             |             |             |
    |------------>|             |             |             |
    |  302 Moved  |             |             |             |
    |<------------|             |             |             |
    |    ACK      |             |             |             |
    |------------>|             |             |             |
    |       INVITE              |             |             |
    |-------------------------->|     ARQ     |             |
    |             |             |------------>|             |
    |             |             |     ACF     |             |
    |             |             |<------------|             |
    |             |             |   Setup     |             |
    |             |             |------------>|   Setup     |
    |             |             |             |------------>|
    |             |             |             |    ARQ      |
    |             |             |             |<------------|
    |             |             |             |    ACF      |
    |             |             |             |------------>|
    |             |             |             |  Alerting   |
    |             |             |   Alerting  |<------------|
    |             |180 Ringing  |<------------|             |

    |180 Ringing  |<------------|             |             |
    |<------------|             |             |   Connect   |
    |             |             |   Connect   |<------------|
    |             |             |<------------|             |
    |             |             |           H.245           |
    |       200 OK              |<------------------------->|
    |<--------------------------|             |             |
    |         ACK               |             |             |
    |-------------------------->|             |             |
    |             |            RTP            |             |
    |<=====================================================>|



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g) Call from SIP terminal to H.323 terminal using H.245 tunneling.

  SIP           SIP                       H.323          H.323
    EP          Proxy          IWF           GK            EP
    |             |             |             |             |
    |  INVITE     |             |             |             |
    |------------>|  INVITE     |             |             |
    |             |------------>|Setup(tunn.= |             |
    |             |             |true,MSD,TCS)|             |
    |             |             |------------>|             |
    |             |             |     ARQ     |             |
    |             |             |<------------|             |
    |             |             |     ACF     |             |
    |             |             |------------>| Setup(MSD,  |
    |             |             |             | TCS)        |
    |             |             |             |------------>|
    |             |             |             |    ARQ      |
    |             |             |             |<------------|
    |             |             |             |    ACF      |
    |             |             |             |------------>|
    |             |             |             |Alerting(MSD |
    |             |             |             |Ack,TCS Ack, |
    |             |             |             |TCS,MSD)     |
    |             |             |Alerting(MSD |<------------|
    |             |             |Ack,TCS Ack, |             |
    |             |             |TCS,MSD)     |             |
    |             | 180 Ringing |<------------|             |
    | 180 Ringing |<------------|             |             |
    |<------------|             |Facility(TCS |             |
    |             |             |Ack,MSD Ack, |             |
    |             |             |OLC)         |             |
    |             |             |------------>|Facility(TCS |
    |             |             |             |Ack,MSD Ack, |
    |             |             |             |OLC)         |
    |             |             |             |------------>|
    |             |             |             |Facility(OLC |
    |             |             |             |Ack,OLC)     |
    |             |             |Facility(OLC |<------------|
    |             |             |Ack,OLC)     |             |
    |             |             |<------------|             |
    |             |             |Facility(OLC |             |
    |             |             |Ack)         |             |
    |             |             |------------>|Facility(OLC |
    |             |             |             |Ack)         |
    |             |             |             |------------>|
    |             |             |             |   Connect   |
    |             |             |   Connect   |<------------|
    |             |    200 OK   |<------------|             |
    |   200 OK    |<------------|             |             |
    |<------------|             |             |             |
    |     ACK     |             |             |             |
    |------------>|    ACK      |             |             |
    |             |------------>|             |             |
    |             |            RTP            |             |
    |<=====================================================>|
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h) Call from SIP terminal to H.323 terminal using early H.245.

   SIP           SIP                       H.323          H.323
    EP          Proxy          IWF           GK            EP
    |             |             |             |             |
    |  INVITE     |             |             |             |
    |------------>|   INVITE    |             |             |
    |             |------------>|Setup(H245   |             |
    |             |             |------------>|Setup(H245   |
    |             |             |Address)     |------------>|
    |             |             |             | Address)


    |             |             |  H245 starts here         |
    |             |             |<------------------------->|
    |             |             |             |  Alerting   |
    |             |             |  Alerting   |<------------|
    |             | 180 Ringing |<------------|  Connect    |
    | 180 Ringing |<------------|   Connect   |<------------|
    |<------------|             |<------------|             |
    |             |             |  H245  ends up to this    |
    |             |    200 OK   |<------------------------->|
    |   200 OK    |<------------|             |             |
    |<------------|             |             |             |
    |    ACK      |             |             |             |
    |------------>|     ACK     |             |             |
    |             |------------>|             |             |
    |             |            RTP            |             |
    |<=====================================================>|




i) Call from SIP terminal to H.323 terminal using fast connect
procedure.

   SIP           SIP                       H.323          H.323
    EP          Proxy          IWF           GK            EP
    |             |             |             |             |
    |             |             |             |             |
    |   INVITE    |             |             |             |
    |------------>|     INVITE  |             |             |
    |             |------------>|    ARQ      |             |
    |             |             |------------>|             |
    |             |             |     ACF     |             |
    |             |             |<------------|             |
    |             |             | Setup(with  |             |
    |             |             | fast start  |             |
    |             |             | and OLC)    |             |
    |             |             |------------>| Setup(with  |
    |             |             |             | fast start  |
    |             |             |             | and OLC)    |
    |             |             |             |------------>|
    |             |             |             |      ARQ    |
    |             |             |             |<------------|

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    |             |             |             |      ACF    |
    |             |             |             |------------>|
    |             |             |             |Alerting(with|
    |             |             |             |fast start)  |
    |             |             |Alerting(with|<------------|
    |             |             |fast start)  |             |
    |             | 180 Ringing |<------------|             |
    | 180 Ringing |<------------|             |             |
    |<------------|             |             |Connect(with |
    |             |             |             |fast start   |
    |             |             |             |and OLC)     |
    |             |             |Connect(with |<------------|
    |             |             |fast start   |             |
    |             |             |and OLC)     |             |
    |             |    200 OK   |<------------|             |
    |   200 OK    |<------------|             |             |
    |<------------|             |             |             |
    |     ACK     |             |             |             |
    |------------>|      ACK    |             |             |
    |             |------------>|             |             |
    |             |            RTP            |             |
    |<=====================================================>|



11. State Machine

This section defines the state machine for a basic call.  The
state machine for complex calls will be defined in next release of this
draft. (This is a draft proposal and will be refined as more analysis
will be done for all call scenarios.)

This section includes only those  RAS messages which are defined for
H.323 terminal/gateway in Section 7.7 Table 19/H.225 [12]. This section
includes only those Q.931 messages which are defined for a H.323
terminal/gateway in Section 7.1/H.225 [12]. This section includes only


a partial list of H.245 messages, which may be required for a basic
call. This section includes only a partial list of SIP messages, which
may be required for a basic call. This section use the Timers defined
in SIP[3], H.225 [12] and Table 9-1/Q.931 [14].

Only messages related to a call are listed as possible messages/events.
All other noncall related messages like RRQ, Register will not be
handled by the call state machine and these messages will be treated as
precall messages. The behavior of the IWF and handling of these
messages are explained in Section 10.1







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11.1  State machine (SIP to H.323)
-----------------------------------

                            +-------------------------+
          +---------------->+          Idle           +<------------+
          |                 +---+---------------+-----+             |
          |                     |               |                   |
          |                     |  INVITE/ARQ   |                   |
          |                     V               |                   |
          |    ARJ    +-----------------+       |                   |
          +<----------+    WaitForAdm   |       | INVITE(PreGranted |
          |           +---------+-------+       |    ARQ or GK      |
          |                     | ACF/Setup     |    not present)/  |
          |                     V               V  Setup            |
          |     T303        +-------------------------+   RLC       |
          +<----------------+     WaitForAlerting     +------------>+
          |                 +---+--------+------+-----+             |
          |        Call Proc.   |  ^     |      |                   |
          |                     |  |     |      |                   |
          |                     +--+     |      |                   |
          |                              |      |  Connect/         |
          |                              |      |  180 Ringing      |
          |                              |      |                   |
          |                    Alerting/ |      |                   |
          |                 180 Ringing  |      |                   |
          |                              V      V                   |
          |     T301        +-------------------------+   RLC       |
          +<----------------+    WaitForH245Complete  +------------>+
          |                 +---+--------+------------+             |
          |                     |   ^    |                          |
          |            Connect  |   |    |                          |
          |                     +---+    |  H245Complete/           |
          |                              |     200 OK               |
          |                              |                          |
          |                              V                          |
          |     BYE         +-------------------------+    RLC      |
          +<----------------+        Connected        +------------>+
                            +-------------------------+


Figure 2: State machine for SIP to H.323 call.


11.2 SIP-H.323 State Machine Behavior For Various Events
--------------------------------------------------------

State : Idle

Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------

RAC                 Non Triggering     Sec.11.2.1       Sec.11.2.1
INVITE              Triggering         Sec.11.2.2       Sec.11.2.2


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All unexpected messages in this state will cause an error indication.
All other messages will be either Non Triggering or for further study.

11.2.1 RAC

If this RAC is for the previous RAI (almostOutOfResources =
true) then do not accept new calls. If this RAC is for a previous RAI
having almostOutOfResources = false, then accept new calls. The RAI
action will be taken by H.323 GK for calls coming from H.323 network.

11.2.2 INVITE

100 Trying SHALL be sent immediately after receiving INVITE.

        (i) If a INVITE message is received in "Idle" state, then send
ARQ to H.323 GK (if it is present in the network, i.e. IWF is
registered to a H.323 GK).


      Next State: WaitForAdm (Waiting For Admission)

        (ii)If IWF has a preGranted ARQ or if no H.323 GK is present in
network (i.e.IWF is not registered with any H.323 GK), then send H.225
Setup message. Setup is sent when the IWF can resolve the IP Address to
which the message has to be sent, e.g., when it has pregranted ARQ, or
the SIP URI gives the H.323 host name. This MAY involve H.323 LRQ/LCF
messages, but does not alter the state of the call. If the H.323 IP
address is not known or can not be resolved then IWF sends back 404 Not
Found.

      Next State: WaitForAlerting

State : WaitForAdm (Waiting For Admission)

Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------
ACF                 Triggering         Send Setup,
WaitForAlerting
ARJ                 Triggering         Send 4xx          Idle
DRQ                 Non Triggering     Send 4xx,Send DCF Idle
RAC                 Non Triggering     See 11.2.1

State : WaitForAlerting (Waiting For Alerting)

Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------
DRQ                 Non Triggering     Send 4xx,Send DCF,  Idle
                                       Send RLC.
RAC                 Non Triggering     See 11.2.1
SetupAcknowledge    Non Triggering     Sec.11.2.3        See 11.2.3
CallProceeding      Non Triggering
Alerting            Triggering         Send 180 Ringing
WaitForH245Complete
Connect             Triggering         Send 180 Ringing

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WaitForH245Complete
ReleaseComplete     Triggering         Send 4xx,Send DRQ  Idle
T303(first exp.)    Non Triggering     Send Setup
T303(second exp.)   Triggering         Send4xx,Send RLC   Idle
TCS                                    See 11.2.4        See 11.2.4
TCS Ack                                See 11.2.4        See 11.2.4

MSD                                    See 11.2.4        See 11.2.4
MSD Ack                                See 11.2.4        See 11.2.4
OLC                                    See 11.2.4        See 11.2.4
OLC Ack                                See 11.2.4        See 11.2.4
UserInputInd                           See 11.2.4        See 11.2.4
EndSession                             See 11.2.4        See 11.2.4
INVITE                                 FFS               FFS
CANCEL             Triggering          Send 4xx,Send DRQ   Idle


11.2.3 If a SetupAcknowledge is received by an IWF from H.323 network
       after sending Setup message, then additional addressing
       information should be sent using INFORMATION messages. If the
       address is incomplete and the canOverlapSend field set to FALSE,
       the call should be dropped using RELEASE COMPLETE.

11.2.4 If the Setup message  contains the fastStart or tunnelled
       H.245 messages, then all H.245 messages will be handled normally
       according to H.245 call handling procedures. It  MAY be  needed
       to open a H.245 channel between the IWF and the H.323
       terminal/Gatekeeper. H245Complete event is initiated when the
       media channels between the caller and callee are open in both
       directions.
       When H.245 is complete, 200 OK SHALL be sent to SIP network.

State : WaitForH245Complete (Waiting For H.245 Complete)

Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------
DRQ                 Non Triggering     Send 4xx,Send DCF  Idle
                                       Send RLC.
RAC                 Non Triggering     See 11.2.1

Connect             Non Triggering     No action req.
ReleaseComplete     Triggering         Send 4xx,Send DRQ  Idle
T301                Triggering         Send 4xx,Send RLC
TCS                                    See 11.2.4        See 11.2.4
TCS Ack                                See 11.2.4        See 11.2.4
MSD                                    See 11.2.4        See 11.2.4
MSD Ack                                See 11.2.4        See 11.2.4

OLC                                    See 11.2.4        See 11.2.4
OLC Ack                                See 11.2.4        See 11.2.4
UserInputInd                           See 11.2.4        See 11.2.4
EndSession                             See 11.2.4        See 11.2.4



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H245 Complete      Triggering          See 11.2.4        CallConnected
INVITE                                 FFS               FFS
CANCEL             Triggering          Send 4xx,Send DRQ   Idle


State : CallConnected (Call Connected)


Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------
DRQ                 Non Triggering     Send 4xx,Send DCF  Idle
                                       Send RLC
RAC                 Non Triggering     See 11.2.1
ReleaseComplete     Triggering         Send 4xx,Send DRQ  Idle
TCS                                    See 11.2.4        See 11.2.4
TCS Ack                                See 11.2.4        See 11.2.4
MSD                                    See 11.2.4        See 11.2.4
MSD Ack                                See 11.2.4        See 11.2.4
OLC                                    See 11.2.4        See 11.2.4
OLC Ack                                See 11.2.4        See 11.2.4
UserInputInd                           See 11.2.4        See 11.2.4
EndSession                             See 11.2.4        See 11.2.4
INVITE                                 FFS               FFS
CANCEL             Triggering          Send 4xx,Send DRQ   Idle































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11.3 State Machine (H323 to SIP)
--------------------------------

                            +-------------------------+
          +---------------->+          Idle           +<------------+
          |                 +---+---------------+-----+             |
          |                     |               |                   |
          |                     | Setup/ARQ     |                   |
          |                     V               |                   |
          |   ARJ/RLC +-----------------+       |                   |
          +<----------+    WaitForAdm   |       | Setup/INVITE      |
          |           +---------+-------+       |  (Pregranted ARQ  |
          |                     | ACF/INVITE    |   or GK not       |
          |                     |               |   present)        |
          |                     |               |                   |
          |                     | 100 Trying    |                   |
          |                     |               |                   |
          |                     |  +-------+    |                   |
          |                     |  |       |    |                   |
          |                     V  |       V    V                   |
          |    CANCEL       +------+------------------+    RLC      |
          +<----------------+      WaitForRinging     +------------>|
          |                 +-------------------------+             |
          |                     |               |                   |
          |                     |180 Ringing/   | 200 OK/           |
          |                     |  Alerting     |   Connect         |
          |                     V               V                   |
          |    BYE or CANCEL+--------------------------+   RLC      |
          +<----------------+ WaitForChannelsConnected +----------->+
          |                 +---+--------+-------------+            |
          |                     |   ^    |                          |
          |       200 OK/Connect|   |    |                          |
          |                     +---+    | H245Complete/            |
          |                              |ACK                       |
          |                              |                          |
          |                              V                          |
          |     BYE         +-------------------------+    RLC      |
          +<----------------+     CallConnected       +------------>+
                            +-------------------------+



Figure 3: State machine for H.323 to SIP call.


11.4 H.323-SIP State Machine Behavior For Various Events
-------------------------------------------


State : Idle
Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------
RAC                 Non Triggering     Sec.11.2.1       Sec.11.2.1
Setup               Triggering         Sec.11.4.1       Sec.11.4.1

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11.4.1 Setup


IWF SHALL send the Call Proceeding message immediately after
receiving Setup message.

        (i) If a Setup message is received in "Idle" state, then send
ARQ to H.323 GK (if it is present in the network, i.e. IWF is
registered to a H.323 GK).

      Next State: WaitForAdm (Waiting For Admission)

        (ii)If IWF has a preGranted ARQ or if no H.323 GK is present in
network (i.e.IWF is not registered with any H.323 GK), then send INVITE
message.

      Next State: WaitForRinging

11.4.2 The Setup message will  contains the fastStart or tunnelled
       H.245 messages,  all H.245 messages will be handled normally
       according to H.245 call handling procedures. It MAY be  needed
       to  open a H.245 channel between the IWF and the H.323
       terminal/Gatekeeper.

       H245Complete event is initiated when the media channels between
       the caller and callee are open in both directions.
       When H.245 is complete, ACK SHALL be sent to SIP network.

State : WaitForAdm (Waiting For Admission)
Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------

ACF                 Triggering         Send INVITE      WaitForRinging
ARJ                 Triggering         Send RelComp     Idle
RAC                 Non Triggering     Sec.11.2.1       Sec.11.2.1
ReleaseComplete     Triggering         Send DRQ, CANCEL    Idle




State : WaitForRinging
Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------
BRQ                 FFS                FFS
RAC                 Non Triggering     Sec.11.2.1       Sec.11.2.1
DRQ                 Triggering         Send DCF,CANCEL,RLC    Idle
ReleaseComplete     Triggering         Send DRQ, CANCEL   Idle
TCS                                    See 11.4.2        See 11.4.2
TCS Ack                                See 11.4.2        See 11.4.2
MSD                                    See 11.4.2        See 11.4.2
MSD Ack                                See 11.4.2        See 11.4.2
OLC                                    See 11.4.2        See 11.4.2
OLC Ack                                See 11.4.2        See 11.4.2


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UserInputInd                           See 11.4.2        See 11.4.2
EndSession                             See 11.4.2        See 11.4.2
100 Trying          Non Triggering      No action
180 Ringing         Triggering         Send Alerting     WaitFor
                                                         Channels
                                                         Connected
200 OK              Triggering         Send Connect      WaitFor
                                                         Channels
                                                         Connected
BYE                 Triggering         Send DRQ,RLC      Idle


State : WaitForChannelsConnected
Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------

BRQ                 FFS                FFS
RAC                 Non Triggering     Sec.11.2.1       Sec.11.2.1
DRQ                 Triggering         Send DCF,RLC     Idle
                                       Send BYE/CANCEL
ReleaseComplete     Triggering         Send DRQ         Idle
                                       Send BYE/CANCEL
TCS                                    See 11.4.2        See 11.4.2
TCS Ack                                See 11.4.2        See 11.4.2
MSD                                    See 11.4.2        See 11.4.2
MSD Ack                                See 11.4.2        See 11.4.2
OLC                                    See 11.4.2        See 11.4.2


OLC Ack                                See 11.4.2        See 11.4.2
UserInputInd                           See 11.4.2        See 11.4.2
EndSession                             See 11.4.2        See 11.4.2
H245 Complete       Triggering         Send ACK          CallConnected
200 OK              Triggering         Send Connect
BYE                 Triggering         Send DRQ,RLC        Idle



State : CallConnected
Possible Messages   Message Category   Action           Next state
-----------------   ----------------   ----------       ----------

BRQ                 FFS                FFS
RAC                 Non Triggering     Sec.11.2.1       Sec.11.2.1
DRQ                 Triggering         Send DCF,BYE,RLC  Idle
ReleaseComplete     Triggering         Send DRQ,BYE      Idle
TCS                                    See 11.4.2        See 11.4.2
TCS Ack                                See 11.4.2        See 11.4.2
MSD                                    See 11.4.2        See 11.4.2
MSD Ack                                See 11.4.2        See 11.4.2
OLC                                    See 11.4.2        See 11.4.2
OLC Ack                                See 11.4.2        See 11.4.2



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UserInputInd                           See 11.4.2        See 11.4.2
EndSession                             See 11.4.2        See 11.4.2
H245 Complete       Triggering         Send ACK          CallConnected
BYE                 Triggering         Send DRQ,RLC        Idle



12. Implementation Requirements

* Terminal Number for the SIP-H323 IWF for H.323 master-slave (MS)
determination SHALL be Gateway without MC.

* DTMF on H323 side SHALL be carried by User Input Indication. Since
there is no media processing in IWF, so the DTMF carried in RTP streams
(like in MicroSoft's Netmeeting) SHALL not be transferred to the SIP
side. DTMF on SIP side MAY be carried by SIP INFO method.


* The gateway MAY replicate DTMF digits (received from the SIP network)
via H.245 UserInputIndications. No DTMF timing information is sent with
H.245v2 UserInputIndications. Therefore,  the default
DTMF time and inter digit timing definitions MAY Need to be used for future versions to
insure that DTMF digits are properly played out into the SIP network.

* An alternative method of sending DTMF (besides UserInputIndications)
is via a separate RTP stream using the IETF draft(draft-ietf-avt-dtmf-
00.txt). If when finalized, this draft meets with the VoIP forums
approval, then it will be specified as an optional method that
endpoints MAY use for DTMF carriage.

* Some Call flow examples shows a delayed "ACK" on SIP side. In
practical cases, this MAY trigger a timeout on SIP side. In these
cases, SIP re-INVITE will be used and ACK will be sent immediately after
getting 200 OK.

* Re-INVITE will be used when necessary. However, the use of reinvite
will be avoided because the SIP endpoint MAY not support it.

*   IWF will contain a look up table which may be used for address
resolution in cases when H.323 GK or SIP Server doesn't exist in the
network. This lookup table MAY also be used in conjunction with
H.323 GK and/or SIP Server.

* Registration messages in most of the cases for the H.323 and SIP
system will be limited to their domain only. IWF in this case will be a
part of both SIP and H.323 domain. This strategy will help in keeping a
distributed data for address resolution. This will also help in making
a scalable solution. This will be discussed in more detail in Phase 2.

* Set the Destination information in H.323 Call Proceeding and Alerting
as "gateway" to specify that the call is routed through IWF.



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* mediaWaitForConnect in H.323 Setup will be set to "false" unless the
endpoint is ready for receiving media immediately or if there is a
mechanism to buffer the media traffic.

* callType for basic calls in H.323 Setup will be set to
"pointTopoint".


* Set the mc=FALSE and undefinedNode=FALSE in the registration message
to H.323 network.

* The IWF SHOULD support the Q.931 messages listed in Table 3. An entry
of "not applicable" in the table means that it is not visible to the
SIP endpoint and is only local to the IWF's H.323 stack.


         Message           IWF sends to H.323  H.323 sends to IWF
         ________________________________________________________
         Alerting          Supported           Supported
         Call proceeding   Supported           Supported
         Connect           Supported           Supported
         Progress          Not applicable      Not applicable
         Setup             Supported           Supported
         Setup Ack         Supported           Not applicable
         Release Complete  Supported           Supported
         User Information  Not applicable      Not applicable
         Information       Supported           Supported
         Notify            Not applicable      Not applicable
         Status            Not applicable      Not applicable
         Status Inquiry    Not applicable      Not applicable
         Facility          Supported           Supported


   Table 3: Support for Q.931 messages

  The IWF MUST NOT close the call signaling channel after the call is
  established. However, if the call is routed through a gatekeeper and
  the gatekeeper closes the call signaling channel, the IWF MUST
  comply with H.323 and MUST NOT assume that the call is closed as long
  as H.245 channel is open. If the Q.931 TCP connection is closed
  without closing the call signaling channel, then the IWF SHOULD try
  reopening the TCP connection, as specified by H.323. In case of
  failure such as TCP connection refused or TCP connection timeout, the
  IWF SHOULD close the call on the SIP side also by sending a BYE.

   Q.931-specific information elements, other than user-user
  information element (UUIE), do not affect the operation of this IWF,
  however they are required for interoperation with other H.323

  entities. The specific fields of UUIE used in translating to SIP
  message are given in Section .

   Bearer Capability:


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             Information transfer capability (octet 3, bits 0--5):
                 Unless some other restrictions apply (e.g., the IWF is
                 connected to a bandwidth-restricted ISDN network), the
                 parameter SHOULD be set to "unrestricted digital
                 information" or "restricted digital information" on
                 outgoing side. If the IWF knows that the call is going
                 to be voice only, it may choose to set it as "speech"
                 or "3.1 kHz Audio". The IWF ignores this field on
                 incoming requests.

             Information Transfer Rate and Rate multiplier:  If
                 bandwidth information is available from the gatekeeper
                 or some external means (e.g., from bandwidth
                 information in SDP message), then information transfer
                 rate and rate multiplier may be set to values
                 reflecting the bandwidth, else they should be set to
                 some high value as appropriate. This way the bandwidth
                 is not limited to 64 kb/s or 128 kb/s. On the incoming
                 side these values SHOULD be ignored. Note that in
                 Q.931 message the only possible values are multiples
                 of 64 kb/s.

             Layer 1 protocol (octet 5, bits 1--5):  For outgoing Q.931
                 messages, the parameter is set to H.221 ('00101'),
                 indicating an H.323 video phone call, unless the IWF
                 knows that the call is going to be voice only (e.g.,
                 if this is hardcoded in the IWF). In that case, it may
                 encode the parameter as G.711 A-law or mu-law to
                 indicate this.
                 For incoming Q.931 messages, the IWF ignores this
                 field.

             Calling or Called party number:  For outgoing Q.931
                 messages, the IWF translates the SIP request-URI into
                 an e164 number, as described in Section 6. The
                 calling/called party subaddress is not included in
                 Q.931 messages originating from the IWF.

                 For incoming Q.931 messages, the IWF
                 relies on user-user information element for addresses
                 e.g., sourceAddress and destinationAddress fields of
                 UUIE) and ignores the Q.931 parameter. However, if the
                 calling/called party number is present and e164-ID is
                 not present in the H.323 Alias Address then the
                 calling/called party number is used instead of e164-ID
                 while translating address in section 8.

                 H.323 specifies that the called and calling party
                 Subaddress fields are needed for some circuit switched
                 call scenarios and they SHOULD NOT be used for packet
                 based network side only calls.

            Display:  For incoming Q.931 messages, the IWF MAY copy the
                 Display IE to the display parameter of the SIP To

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                 header field.Similarly, for outgoing Q.931 messages,
                 the Display parameter MAY be copied from the display
                 parameter of the SIP To field.

            Cause:  For incoming Q.931 messages, the Q.931 Cause
                   information element and/or the UUIE reason field are
                 mapped to the appropriate SIP status response code, as
                 described in Table 1. H.225.0 [12] specifies that
                 either the Cause information element or the
                 releaseCompleteReason MUST be present. It also gives a
                 mapping between the Cause information element and the
                 releaseCompleteReason. Table 1 gives the mapping
                 between releaseCompleteReason and the appropriate SIP
                 status response. Similarly, for outgoing Q.931 messages,
                 the Q.931 Cause information element and the UUIE reason
                 field are derived according to Table 1.

            User-User-Information-Element:  Below, we detail the fields
                  in UUIE which are relevant to H.323-SIP conversion.
                  Other fields are interpreted as defined by H.225.0.

            sourceInfo/destinationInfo: In all messages from the IWF,
                 this field SHOULD be set to indicate that this
                 endpoint is a gateway. However, the sequence of
                 supported protocols in "GatewayInfo" may be empty.
                 H.245SecurityMode, tokens, cryptoTokens: These fields
                 are interpreted as in H.323. Note that since H.245 is
                 terminated at the IWF, this kind of security
                 information is not relevant to the SIP cloud.
                 (Security issues will be addressed in the next phase.)

            fastStart: FastStart PDUs contain the OpenLogicalChannel
                 OLC) messages. The IWF  converts incoming OLC messages
                 to a SDP message body. One SDP media description line
                 ("m=") is  generated for each distinct session-ID. All
                 logical channels with same session-ID appear as
                 payload types in a single SDP media description line.
                 When converting SIP to H.323, the SDP  message is
                 converted to a list of OpenLogicalChannel messages,
                 one per payload type. H.323 endpoint will select
                 atmost one OLC per session-ID.  This selected OLC is
                 returned by the H.323 endpoint in the fastStart field
                 of Q.931 Connect message. When converting H.323 to
                 SIP, each OLC in fastStart corresponds to a payload
                 type of SDP.  All the OLC messages with same session-
                 ID form a single media description ("m=") line.

The parameters for the Q.931 SETUP message are listed below.

             sourceAddress: Converted to/from SIP header From field as
                 described in section 8.

             destinationAddress: Converted to/from SIP header To field
                 as described in section 8.

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             destCallSignalAddress: If the To SIP header field contains
                 a numeric host identifier then destCallSignalAddress
                 is set to the IPv4 address represented by the numeric
                 identifier.

             conferenceGoal: Set to "create" in outgoing Q.931
                 messages. (Additional values may be supported in
                 future versions of this specification that support
                 conferencing.)

             remoteExtensionAddress: Not present in outgoing Q.931
                  messages. For incoming Q.931 messages, this parameter
                  is combined with the DestinationAddress parameter to
                  generate the SIP To header field and the request-URI.

             mediaWaitForConnect: Set to "false" in outgoing Q.931
                  messages. Ignored in incoming Q.931 messages, as
                  media transmission is transparent to the IWF.

         Table 4 details how an IWF handles H.245 messages.  An entry
of "not applicable" means that the message does not affect the behavior
within the SIP cloud.


The remainder of this subsection lists the possible values of some of
the fields of H.245 messages. Refer to H.245 version 3.0 for
description and details of the ASN.1 structures for H.245.

        MasterSlaveDetermination: The terminalType parameter is set to
             indicate that this terminal is a gateway.  H.323 specifies
             a set of numerical values of terminalType for different
             types of terminals.  For example, a gateway without a
             multipoint controller (MC) has a terminalType of 60; A
            gateway with a MC and no multipoint processor (MP) has a
            terminalType value of 80.  Other values of terminalType are
            not relevant to this IWF in the case where media traffic is
            transparent.  See H.323 [5] for other possible values of
            terminalType.


     Message                               REQUIRED or Not applicable
     MasterSlaveDetermination/Ack/Rej/Rel  Not Applicable
     TerminalCapSet/Ack/Reject/Release     REQUIRED
     Send TerminalCapabilitySet            REQUIRED
     OpenLogicalChannel/Ack/Reject         REQUIRED
     OpenLogicalChannelConfirm             Not Applicable
     CloseLogicalChannel/Ack               REQUIRED
     RequestChannelClose                   OPTIONAL
     RequestMode/Ack/Rej/Rel               RECOMMENDED
     RoundTripDelayReq/Res                 Not applicable
     MaintenanceLoopReq/Ack/Reject         Not supported
     MaintenanceLoopOffCmd                 Not supported
     CommunicationModeReq/Res/Cmd          For further study
     ConferenceReq/Res/Cmd/Indic           For further study

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     EndSessionCommand                     REQUIRED
     FlowControlCommand                    For further study
     Encryption Command                    For further study
     Jitter Indication                     For further study
     User Input                            REQUIRED
     H2250MaxSkewIndic                     For further study
     MClocationIndication                  For further study
     FunctionNotUnderstood                 Not Applicable
     FunctionNotSupported                  Not Applicable
     vendorIdentifier                      Not Applicable
     MiscCommand/Indication                For further study


   Table 4: Support for H.245 messages.

   An entry  of  "not  applicable"    means that it is not visible to
the SIP endpoint and is only local to the IWF's H.323 stack.

        TerminalCapabilitySet:

             multiplexCapability::h2250Capability:
                  maximumAudioDelayJitter should be set to maximum
                  possible
                  value as specified by H.323.  MultipointCapabilities
                  should reflect minimum capability of Centralized
                  Control/ Audio/ Video/ Data.  Other conferencing


                  capabilities are for further study.  RTCP
                  videoControlCapability should be set to false because
                  anyway H.245 indications have to be used for this
                  purpose.  MediaPacketizationCapability should contain
                  the information about the dynamic payload types used
                  by SIP endpoint.  Transport Capability should be
                  absent.  redundancyEncodingCapability should be
                  absent. This is not supported in this version.
                  logicalChannelSwitchingCapability may be supported by
                  the IWF's H.323 stack. This makes mapping SIP re-
                  INVITE easier.  t120DynamicPortCapability is set to
                  false because T120 data is not supported in this
                  version.

             CapabilityTableEntry and

             CapabilityDescriptor are mapped from the session
                  description given by SDP. A single capability
                  descriptor is used in H.245. All the payload types on
                  a single media description line (m=) are combined to
                  form an alternative capability set in H.245. All such
                  media description lines are combined to form a
                  simultaneous capability set (or a capability
                  descriptor). Mapping multiple SDP received in
                  multipart body of SIP to multiple capability
                  descriptor is for further study.

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             Capability:

             H233Encryption is not applicable.

             H235Security is not applicable.

             DataApplication capability is not supported in this
             version of the specification.

             ConferenceCapability is for further study and is not
                  supported in this version of the specification.

             UserInputCapability may be supported by the IWF.  This is
                            used to convey DTMF digits. Use of the SIP
             INFO method
                  may be considered for this purpose.

             maxPendingReplacementFor is not applicable.

             Audio and Video: A capability in H.323 represents a
                 payload type.  Refer to
                 http://www.iana.org/assignments/media-types/media-
                 types for a list of MIME types and
                 http://www.iana.org/assignments/rtp-parameters
                 for a list of static RTP payload types. Use of static
                 RTP payload types in SDP is discouraged. The IWF
                 should maintain a list of all currently available
                 payload types and media formats and the corresponding
                 RFC numbers. (An intelligent IWF MAY periodically
                 download and parse these HTML pages to update its
                 database).
                       The predefined audio and video
                 capabilities are mapped to appropriate media format
                 and RTP payload type. This mapping is given in this
                 document for ease of reference. This mapping should be
                 used by the IWF to convert the H.323 capability to an
                 SDP media description.  When converting from H.323 to
                 SDP, the IWF SHOULD use dynamic payload type. When
                 converting from SDP to H.323, the IWF SHOULD NOT use
                 dynamic payload types because many current
                 implementations do not support these. However, the IWF
                 MUST be able to receive dynamic payload types, in both
                 H2250Capability.MediaPacketizationCapabilty.RTPPayload
                 Type and in
                 H250LogicalChannelParameters.MediaPacketization. When
                 dynamic RTP payload type are used,
                 H225LogicalChannelParameters.dynamicRTPPayloadType
                 MUST match the payload type description given in
                 mediaPacketization.







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13. Activities Planned for Next Phase

13.1 Simple call supplementary services like call forwarding, call hold
and call transfer.
13.2 Conferencing.
13.3 Session change (re-invite, mode request).
13.4 Security
13.5 QOS signalling.

14. Security Considerations

14.1 Gateway authentication method to SIP side of the IWF.

15. Known Issues

15.1 Resource reservation (RAI of H.323 )mapping in SIP.
15.2 Publishing of IWF dialing range automatically in SIP. At present,
this needs to be configured statically in the SIP servers.
15.3 Support of Location request and mapping of the same in SIP
Servers. Since H.323 terminals/gateway cannot receive LRQ messages (See
Table 19/Section 7.7/H.225 [12]) to resolve addresses, the address
resolution information cannot be properly distributed.
15.4 Support for multiple calls with same Call ID in SIP

16. To Be Done

16.1 Call Flow diagrams does'nt reflect the calculations for finding
the common subset of capabilities. This was not added because of
simplicity and few additional call flow diagrams will be added in next
release of the draft.
16.2 Message parameter mapping giving the details of every possible
mapping will be added in next release of the draft.
16.3 Registration call flow diagrams will be added in the next release
of the draft.
16.4 Call Release flow diagrams will be added in the next release of
the draft.
16.5 Call flows showing SDP media description line ("m=") for each
distinct session-ID of the OLC will be added in the next release of the
draft.
16.6 Treatment of IWF and SIP network as a cluster and defining a zone
from H.323 perspective.
16.7 Transfer of Qos (if any) to SIP network.
16.8 The state machine will be further refined once the detail analysis
of all call flows is completed.

17. Conclusion

This draft is an attempt to define an agreed upon standard for the SIP
and H.323 interworking. It will be updated based on the discussions on
open mailing lists and implementors.





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Appendix A: Calculating common subset of capabilities

The capability set of a terminal or a user agent refers to the set of
algorithms for audio, video and data that it can support. It also
conveys information about constraints in the selection of algorithms
it may have. For example, due to limited bandwidth, a terminal may
indicate that it can use either G.711 without video or G.723.1 with
H.261 video.

The operating mode of a call refers to the selected algorithms which
are used for the actual transfer of media. To determine the
operating mode for a call it is often necessary to find out the
intersection of the capabilities of the endpoints in the conference.
This section presents a way to calculate this intersection of the
capability sets described by H.245 Terminal Capability Set (TCS) and
that by SDP.

A maximal intersection of two capability sets is a capability set
which is a subset of both the capability sets and no other superset
of the maximal intersection is a subset of those capability sets. It
can be proven that if M is an operating mode for capability set C1
as well as for capability set C2, then M will be an operating mode
for maximal intersection of C1 and C2. Thus, we fulfill requirement
X described in Section X.

H.245 defines Terminal Capabilities as a list of capability
descriptors, ordered in decreasing preference. Any one of the
capability descriptors can be used for selecting operating modes.

Each capability descriptor includes a simultaneous capability set.
Each element in the simultaneous capability set is an alternative
capability set. Each element in the alternative capability set
represents an algorithm. Each algorithm has a payload type and can
be fully described by the payload type, a profile and some optional
attributes.

Convention:


   { } capability descriptor or simultaneous capability set
   [ ] alternative capability set






   Example: Let a1, a2, a3, a4, a5 be audio algorithms and v1, v2, v3
   be video algorithms. C1 represents a capability set with two
   capability descriptors:


   C1 = { [a1, a2, a3] [v1, v2] }
        { [a1, a4, a5] [v1] }

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   Operating modes could be (a1, v1), (a1, v2), (a4, v1), (a5), etc.
   Note that (a4, v2) is not an operating mode since a4 and v2 are
   drawn from different capability descriptors.

   Let C2 be another capability set.


   C2 = { [a1, a4, a2] [v1, v2, v3] }
        { [a1, a2, a5] [v1, v3] }





   The maximal intersection of C1 and C2 is


   C = { [a1, a2] [v1, v2] }
       { [a1, a4] [v1] }
       { [a1, a5] [v1] }



Note that there are other capability sets which are intersections of
C1 and C2 (e.g., {[a1,a2][v2]}), but they are subsets of C and hence
can be derived from C.

 Algorithm for Finding Maximal Intersection of Capability Sets
----------------------------------------------------------------

   An algorithm to find the maximal intersection of any two capability
   sets C1 and C2 is given below:

        1.   Set the result C to the empty set.

        2.   For each pair of capability descriptors (d1, d2), where d1
             is from C1 and d2 is from C2, derive the permutations of
             alternative sets, s1 and s2.

             For each such permutation, where s1 is from d1 and s2 is
             from d2, intersect s1 and s2 (written as s=s1 ^ s2) and
             add s to C.

        3.   Remove duplicate entries from C.

   Example: Using the example with C1 and C2 given above, the outer
loop runs for four iterations, since C1 and C2 both have two descriptors.



        1.

              d1 = {[a1,a2,a3][v1,v2]},
              d2 = {[a1,a4,a2][v1,v2,v3]}

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             Inner loop runs for 2 iterations:

                 1) {[a1,a2,a3]^[a1,a4,a2],[v1,v2]^[v1,v2,v3]}
                             = {[a1,a2][v1,v2]}
                 2) {[a1,a2,a3]^[v1,v2,v3],[v1,v2]^[a1,a4,a2]}
                             = {[][]}  /* Empty set */



        2.

              d1 = {[a1,a4,a5][v1]},
              d2 = {[a1,a4,a2][v1,v2,v3]}
                1) {[a1,a4,a5]^[a1,a4,a2], [v1] ^[v1,v2,v3]}
                             = {[a1,a4][v1]}
                2) {[a1,a4,a5]^[v1,v2,v3],[v1]^[a1,a4,a2]}
                             = {[][]}  /* Empty set */



        3.

              d1 = {[a1,a2,a3][v1,v2]},
              d2 = {[a1,a2,a5][v1,v3]}
                1) {[a1,a2,a3]^[a1,a2,a5],[v1,v2]^[v1,v3]}
                             = {[a1,a2][v1]}
                2) {[a1,a2,a3]^[v1,v3],[v1,v2]^[a1,a2,a5]}
                             = {[][]}  /* Empty set */



        4.

              d1 = {[a1,a4,a5][v1]},

              d2 = {[a1,a2,a5][v1,v3]}



                1) {[a1,a4,a5]^[a1,a2,a5],[v1]^[v1,v3]}
                             = {[a1,a5][v1]}
                2) {[a1,a4,a5]^[v1,v3],[v1]^[a1,a2,a5]}
                             = {[][]}  /* Empty set */



   After these iterations the intersection set becomes

    { [a1,a2] [v1,v2] } { }
    { [a1,a2] [v1] } { }
    { [a1,a4] [v1] } { }
    { [a1,a5] [v1] } { }




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   After removing duplicates, the maximal intersection is


    { [a1,a2] [v1,v2] }
    { [a1,a4] [v1] }
    { [a1,a5] [v1] }



   Since H.323 does not require that all algorithms listed within a
   single alternative capability have the same media type, we need the
   inner loop to find out all the possible combinations.

   For example, if C1 = {[a1,a2,a3] [a1,a4,v2,v1]} and C2 = {[a1,a4,v2]
   [v1,v2,v3]}, then the above algorithm correctly finds the
   intersection as {[a1] [v1,v2]} {[a1,a4,v2]}



Appendix B: Advertisement of SIP Support by H.323 Gateways


-----------------------------------------------------------

SupportedProtocols ::= CHOICE {
    nonStandardData NonStandardParameter,
    h310 H310Caps,
    h320 H320Caps,
    h321 H321Caps,
    h322 H322Caps,
    h323 H323Caps,
    h324 H324Caps,
    voice VoiceCaps,
    t120-only T120OnlyCaps,
    ...,
    nonStandardProtocol NonStandardProtocol,
    t38FaxAnnexbOnly T38FaxAnnexbOnlyCaps,
    sip SIPCaps
 }

SIPCaps ::= SEQUENCE
{
    nonStandardData NonStandardParameter OPTIONAL,
    dataRatesSupported SEQUENCE OF DataRate OPTIONAL,
    supportedPrefixes SEQUENCE OF SupportedPrefix,
    ...
}

CallCapacityInfo ::= SEQUENCE {
    voiceGwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    h310GwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    h320GwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    h321GwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    h322GwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    h323GwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,

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    h324GwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    t120OnlyGwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    t38FaxAnnexbOnlyGwCallsAvailable SEQUENCE OF CallsAvailable
OPTIONAL,
    terminalCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    mcuCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL,
    ...,


    sipGwCallsAvailable SEQUENCE OF CallsAvailable OPTIONAL
 }

Appendix C: Message Details of Call Flows
-------------------------------------------------------------

C.1 Simple Call from H.323 terminal to SIP terminal.

Message Details.


F1 Setup H.323 -> IWF


H323-UserInformation
{
   h323-uu-pdu                                  :
     h323-message-body                          :
       setup                                    :
         protocolIdentifier                     : itu-t
                                                : recommendation
                                                : h
                                                : 2250
                                                : version
                                                : 2
         sourceAddress                          :
           e164 address                         : 01000220013101720
           h323-ID address                      : UserA19284
           e164 address                         : 7199557429
         sourceInfo                             :
           vendor                               :
             vendor                             :
               t32CountryCode                   : 11
               t32Extension                     : 11
               manufacturerCode                 : 11
               productId                        : IWF
               versionId                        : SIP-H323
           terminal                             :
           mc                                   : false
           undefinedNode                        : false


         destinationAddress                     :
           h323-ID Address                      : UserB@there.com
         destCallSignalAddress                  :

Agrawal, et al.                                              [Page 64]


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           ipAddress                            :
             ip                                 : 164.164.28.121
             port                               : 1720
         activeMC                               : false
         conferenceID                           : Hex( 56 34 34 34
     34 EF 09 00 21 21 E4 83 2D 7E BA AB )
         conferenceGoal                         : create
         callType                               : pointToPoint
         sourceCallSignalAddress                :
           ipAddress                            :
             ip                                 : 164.164.28.101
             port                               : 3472
         callIdentifier                         :
           guid                                 : Hex( 56 34 34 34
          34 EF 08 00 21 21 E4 83 2D 7E BA AB )
         mediaWaitForConnect                    : false
         canOverlapSend                         : false
     h245Tunneling                              : false
}

Setup specifies the called endpoint address in H323 Id of destination
address. This H323Id will be resolved at the IWF and the destination
call signalling address in this case will be the call signalling
address of IWF. IWF uses the destination alias address for resolving
the  destination endpoint and routes the call to endpoint B.


F2 INVITE IWF -> SIP

INVITE sip:UserB@there.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Contact: <sip:UserA19284@164.164.28.121>
Content-Type: application/sdp
Content-Length: ...

v=0
o=IWF 2890844526 2890844526 IN IP4 164.164.28.121
s=-
c=IN IP4 164.164.28.121
t=3034423619 0
m=audio 5004 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F3 CallProc IWF -> H.323

H323-UserInformation
{
   h323-uu-pdu                                  :
     h323-message-body                          :

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       callproceeding                           :
         protocolIdentifier                     : itu-t
                                                : recommendation
                                                : h
                                                : 2250
                                                : version
                                                : 2
         destinationInfo                        : gateway
         callIdentifier                         : Hex( 56 34 34 34
                                                  34 EF 09 00 21 21 E4
                                                  83 2D 7E BA AB )
}

Call Proceeding will tell the calling endpoint that the call is routed
through a gateway.


F4 (100 Trying) SIP -> IWF

SIP/2.0 100 Trying
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Content-Length: 0


F5 180 Ringing SIP -> IWF

SIP/2.0 100 Trying
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Content-Length: 0


F6 Alerting IWF -> H.323

H323-UserInformation
{
   h323-uu-pdu                                  :
     h323-message-body                          :
       alerting                                 :
         protocolIdentifier                     : itu-t
                                                : recommendation
                                                : h
                                                : 2250
                                                : version
                                                : 2
         destinationInfo                        : gateway


Agrawal, et al.                                              [Page 66]


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         callIdentifier                         : Hex( 56 34 34 34 34
                                                  EF 09 00 21 21 E4 83
                                                  2D 7E BA AB )
}



F7 200 OK IWF -> SIP
SIP/2.0 200 OK
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F8 Connect IWF -> H.323

H323-UserInformation
{
   h323-uu-pdu                                  :
     h323-message-body                          :
       callproceeding                           :
         protocolIdentifier                     : itu-t
                                                : recommendation
                                                : h
                                                : 2250
                                                : version
                                                : 2
         h245Address                            :
           ipAddress                            :
             ip                                 : 164.164.28.141
             port                               : 2000
         destinationInfo                        : gateway
      conferenceID                              : Hex( 56 34 34 34 34
                                                  EF 09 00 21 21 E4 83
                                                  2D 7E BA AB )
         callIdentifier                         : Hex( 56 34 34 34 34
                                                  EF 09 00 21 21 E4 83
                                                  2D 7E BA AB )
}



Agrawal, et al.                                              [Page 67]


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H245 Address specified in Connect message will give the information
about the H.245 channel of endpoint B. This will be used to establish
the H.245 control channel.


F9 ACK IWF -> SIP

ACK sip:UserB@there.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 ACK
Content-Length: 0


F10 TCS H.323 -> IWF

H245 MultimediaSystemControlMessage
{
   request                                             :
     terminalCapabilitySet                             :
       sequenceNumber                                  : 1
       protocolIdentifer                               : itu-t
                                                       : recommendation
                                                       : h
                                                       : 245
                                                       : version
                                                       : 3
       multiplexCapability                             :
         h2250Capability                               :
           maximumAudioDelayJitter                     : 60
           receiveMultipointCapability                 :
             multicastCapability                       : false
             multiUniCastConference                    : false
             mediaDistributionCapability               :
               centralizedControl                      : false
               distributedControl                      : false
               centralizedAudio                        : false
               distributedAudio                        : false
               centralizedVideo                        : false
               distributedVideo                        : false
           transmitMultipointCapability                :
             multicastCapability                       : false
             multiUniCastConference                    : false
             mediaDistributionCapability               :
               centralizedControl                      : false
               distributedControl                      : false
               centralizedAudio                        : false
               distributedAudio                        : false
               centralizedVideo                        : false
               distributedVideo                        : false
           receiveAndTransmitMultipointCapability      :
             multicastCapability                       : false
             multiUniCastConference                    : false

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             mediaDistributionCapability               :
               centralizedControl                      : false
               distributedControl                      : false
               centralizedAudio                        : false
               distributedAudio                        : false
               centralizedVideo                        : false
               distributedVideo                        : false
           mcCapability                                :
             centralizedConferenceMC                   : false
             deCentralizedConferenceMC                 : false
           rtcpVideoControlCapability                  : false
           mediaPacketizationCapability                :
             h261aVideoPacketization                   : false
       capabilityTable                                 :
         capabilityTableEntryNumber                    : 7111
         capability                                    :
           receiveAudioCapability                      :
             g711Ulaw-64k                              : 60
         capabilityTableEntryNumber                    : 7110
         capability                                    :
           receiveAudioCapability                      :
             g711Alaw64k                               : 60
         capabilityTableEntryNumber                    : 728
         capability                                    :
           receiveAudioCapability                      :
             g728                                      : 60
         capabilityTableEntryNumber                    : 261
         capability                                    :
           receiveVideoCapability                      :
             h261VideoCapability                       :
               qcifMPI                                 : 1 [1/29.97 Hz]
               cifMPI                                  : 1 [1/29.97 Hz]
               temporalSpatialTradeOffCapability       : false
               maxBitRate                              : 600 [100
                                                         bit/sec]
               stillImageTransmission                  : false
         capabilityTableEntryNumber                    : 263
         capability                                    :
           receiveVideoCapability                      :
             h263VideoCapability                       :
               sqcifMPI                                : 1 [1/29.97 Hz]
               qcifMPI                                 : 1 [1/29.97 Hz]
               cifMPI                                  : 1 [1/29.97 Hz]
               maxBitRate                              : 1000 [100
                                                         bit/s]
               unrestrictedVector                      : false
               arithmeticCoding                        : false
               advancedPrediction                      : false
               pbFrames                                : false
               temporalSpatialTradeOffCapability       : false
               errorCompensation                       : false
         capabilityTableEntryNumber                    : 7231
         capability                                    :
           receiveAudioCapability                      :
             g7231                                     :

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               maxA1-sduAudioFrames                    : 8
               silenceSuppression                      : false
         capabilityTableEntryNumber                    : 120
         capability                                    :
           receiveAndTransmitDataApplicationCapability :
             application                               :
               t120                                    :
                 separateLANStack                      :
             maxBitRate                                : 1000 [100
                                                         bit/s]
       capabilityDescriptors                           :
         capabilityDescriptorNumber                    : 0
         simultaneousCapabilities                      : 7111 7110 7231
                                                         728
                                                       : 261 263
                                                       : 120
}


F11 TCSAck IWF -> H.323

H245 MultimediaSystemControlMessage
{
   response                                         :
     terminalCapabilitySetAck                       :
       sequenceNumber                               : 1
}


F12 TCS IWF -> H.323
H245 MultimediaSystemControlMessage
{
   request                                             :
     terminalCapabilitySet                             :
       sequenceNumber                                  : 1
       protocolIdentifer                               : itu-t
                                                       : recommendation
                                                       : h
                                                       : 245
                                                       : version
                                                       : 3
       multiplexCapability                             :
         h2250Capability                               :
           maximumAudioDelayJitter                     : 60
           receiveMultipointCapability                 :
             multicastCapability                       : false
             multiUniCastConference                    : false
             mediaDistributionCapability               :
               centralizedControl                      : false
               distributedControl                      : false
               centralizedAudio                        : false
               distributedAudio                        : false
               centralizedVideo                        : false
               distributedVideo                        : false
           transmitMultipointCapability                :

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             multicastCapability                       : false
             multiUniCastConference                    : false
             mediaDistributionCapability               :
               centralizedControl                      : false
               distributedControl                      : false
               centralizedAudio                        : false
               distributedAudio                        : false
               centralizedVideo                        : false
               distributedVideo                        : false
           receiveAndTransmitMultipointCapability      :
             multicastCapability                       : false
             multiUniCastConference                    : false
             mediaDistributionCapability               :
               centralizedControl                      : false
               distributedControl                      : false
               centralizedAudio                        : false
               distributedAudio                        : false
               centralizedVideo                        : false
               distributedVideo                        : false
           mcCapability                                :
             centralizedConferenceMC                   : false
             deCentralizedConferenceMC                 : false
           rtcpVideoControlCapability                  : false
           mediaPacketizationCapability                :
             h261aVideoPacketization                   : false
       capabilityTable                                 :
         capabilityTableEntryNumber                    : 7111
         capability                                    :
           receiveAudioCapability                      :
             g711Ulaw-64k                              : 60
         capabilityTableEntryNumber                    : 7110
         capability                                    :
           receiveAudioCapability                      :
             g711Alaw64k                               : 60
         capabilityTableEntryNumber                    : 728
         capability                                    :
           receiveAudioCapability                      :
             g728                                      : 60
         capabilityTableEntryNumber                    : 261
         capability                                    :
           receiveVideoCapability                      :
             h261VideoCapability                       :
               qcifMPI                                 : 1 [1/29.97 Hz]
               cifMPI                                  : 1 [1/29.97 Hz]
               temporalSpatialTradeOffCapability       : false
               maxBitRate                              : 600 [100
                                                         bit/sec]
               stillImageTransmission                  : false
         capabilityTableEntryNumber                    : 263
         capability                                    :
           receiveVideoCapability                      :
             h263VideoCapability                       :
               sqcifMPI                                : 1 [1/29.97 Hz]
               qcifMPI                                 : 1 [1/29.97 Hz]
               cifMPI                                  : 1 [1/29.97 Hz]

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               maxBitRate                              : 1000 [100
                                                         bit/s]
               unrestrictedVector                      : false
               arithmeticCoding                        : false
               advancedPrediction                      : false
               pbFrames                                : false
               temporalSpatialTradeOffCapability       : false
               errorCompensation                       : false
         capabilityTableEntryNumber                    : 7231
         capability                                    :
           receiveAudioCapability                      :
             g7231                                     :
               maxA1-sduAudioFrames                    : 8
               silenceSuppression                      : false
         capabilityTableEntryNumber                    : 120
         capability                                    :
           receiveAndTransmitDataApplicationCapability :
             application                               :
               t120                                    :
                 separateLANStack                      :
             maxBitRate                                : 1000 [100
                                                         bit/s]
       capabilityDescriptors                           :
         capabilityDescriptorNumber                    : 0
         simultaneousCapabilities                      : 7111 7110 7231
                                                         728
                                                       : 261 263
                                                       : 120


}

F13 TCSAck H.323 -> IWF

H245 MultimediaSystemControlMessage
{
   response                                         :
     terminalCapabilitySetAck                       :
       sequenceNumber                               : 1
}



F14 MSD H.323 -> IWF

H245 MultimediaSystemControlMessage
{
   request                                          :
     masterSlaveDetermination                       :
       terminalType                                 : 50
       statusDeterminationNumber                    : 8524727
}



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F14A MSD IWF -> H.323

H245 MultimediaSystemControlMessage
{
   request                                          :
     masterSlaveDetermination                       :
       terminalType                                 : 60
       statusDeterminationNumber                    : 5996695
}

F15 MSDAck IWF -> H.323

MasterSlaveDeterminationAck

H245 MultimediaSystemControlMessage
{
   response                                         :
     masterSlaveDeterminationAck                    :
       decision                                     : master
}


F16 MSDAck H323 -> IWF

H245 MultimediaSystemControlMessage
{
   response                                         :
     masterSlaveDeterminationAck                    :
       decision                                     : slave
}


F17 OLC H.323 -> IWF

OpenLogicalChannel (RTCP=2327,g711Ulaw)

H245 MultimediaSystemControlMessage
{
   request                                          :
     openLogicalChannel                             :
       forwardLogicalChannelNumber                  : 1
       forwardLogicalChannelParameters              :
         dataType                                   :
           audioData                                :
             g711Ulaw-64k                           : 60
         multiplexParameters                        :
         h2250LogicalChannelParameters              :
           sessionID                                : 1
           mediaControlChannel                      :
             unicastAddress                         :
               iPAddress                            :
                 network                            : 164.164.28.101
                 tsapIdentifier                     : 2327
           transportCapability                      :

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             QOSCapabilities                        :
               rsvpParameters                       :
                 qosMode                            : guaranteedQOS
                 tokenRate                          : 23 [bytes/sec]
                 bucketSize                         : -1 [bytes]
                 peakRate                           : -1 [bytes/sec]
                 minPoliced                         : -1
                 maxPktSize                         : -1 [bytes]
               atmParameters                        :
                 maxNTUSize                         : 10 [octets]
                 atmUBR                             : false
                 atmrtVBR                           : false
                 atmnrtVBR                          : false
                 atmABR                             : false
                 atmCBR                             : true
}


F18 OLCAck IWF -> H.323

OpenLogicalChannelAck (RTP=4326, 164.164.28.141)

H245 MultimediaSystemControlMessage
{
   response                                         :
     openLogicalChannelAck                          :
       forwardLogicalChannelNumber                  : 1
       forwardMultiplexAckParameters                :
         h2250LogicalChannelAckParameters           :
           sessionID                                : 1
           mediaChannel                             :
             unicastAddress                         :
               iPAddress                            :
                 network                            : 164.164.28.141
                 tsapIdentifier                     : 4326
           mediaControlChannel                      :
             unicastAddress                         :
               iPAddress                            :
                 network                            : 164.164.28.141
                 tsapIdentifier                     : 4327
           flowControlToZero                        : true
}

F19 OLC IWF -> H.323

OpenLogicalChannel (RTCP=4347,g711Ulaw)

H245 MultimediaSystemControlMessage
{
   request                                          :
     openLogicalChannel                             :
       forwardLogicalChannelNumber                  : 1
       forwardLogicalChannelParameters              :
         dataType                                   :

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           audioData                                :
             g711Ulaw-64k                           : 60
         multiplexParameters                        :
         h2250LogicalChannelParameters              :
           sessionID                                : 1
           mediaControlChannel                      :
             unicastAddress                         :
               iPAddress                            :
                 network                            : 164.164.28.141
                 tsapIdentifier                     : 4327
}

F20 OLCAck H.323 -> IWF

OpenLogicalChannelAck (RTP=2326, 164.164.28.101)

H245 MultimediaSystemControlMessage
{
   response                                         :
     openLogicalChannelAck                          :
       forwardLogicalChannelNumber                  : 1
       forwardMultiplexAckParameters                :
         h2250LogicalChannelAckParameters           :
           sessionID                                : 1
           mediaChannel                             :
             unicastAddress                         :
               iPAddress                            :
                 network                            : 164.164.28.101
                 tsapIdentifier                     : 2326
           mediaControlChannel                      :
             unicastAddress                         :
               iPAddress                            :
                 network                            : 164.164.28.101
                 tsapIdentifier                     : 2327
           flowControlToZero                        : true
}

F21 INVITE IWF -> SIP

INVITE sip:UserB@there.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Contact: <sip:UserA19284@164.164.28.121>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserA 2890844526 2890844526 IN IP4 164.164.28.101
s=-
c=IN IP4 164.164.28.101
t=3034423619 0

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m=audio 2326 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F22 200 OK SIP -> IWF

SIP/2.0 200 OK
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F23 ACK IWF -> SIP

ACK sip:UserB@there.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 ACK
Content-Length: 0

------------------------------------------------------------------


C.2 Call from H.323 terminal to SIP terminal using H.245 tunneling

Message Details.

F1 Setup H.323 -> IWF

Setup UserB@there.com

H323-UserInformation
{
   h323-uu-pdu                                  :
     h323-message-body                          :
       setup                                    :
         protocolIdentifier                     : itu-t
                                                : recommendation
                                                : h

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                                                : 2250
                                                : version
                                                : 2
         h245Address                            :
           ipAddress                            :
             ip                                 : 164.164.28.101
             port                               : 2000
         sourceAddress                          :
           e164 address                         : 01000220013101720
           h323-ID address                      : UserA@here.com
           e164 address                         : 7199557429
         sourceInfo                             :
           vendor                               :
             vendor                             :
               t32CountryCode                   : 11
               t32Extension                     : 11
               manufacturerCode                 : 11
               productId                        : IWF
               versionId                        : SIP-H323
           terminal                             :
           mc                                   : false
           undefinedNode                        : false
         destinationAddress                     :
           h323-ID address                      : UserB@there.com
         destCallSignalAddress                  :
           ipAddress                            :
             ip                                 : 164.164.28.121
             port                               : 1720
         activeMC                               : false
         conferenceID                           : Hex( 56 34 34 34
                                                  34 EF 09 00 21 21 E4
                                                  83 2D 7E BA AB )
         conferenceGoal                         : create
         callType                               : pointToPoint
         sourceCallSignalAddress                :
           ipAddress                            :
             ip                                 : 164.164.28.101
             port                               : 3472
         callIdentifier                         :
           guid                                 : Hex( 56 34 34 34
                                                  34 EF 08 00 21 21 E4
                                                  83 2D 7E BA AB )
         mediaWaitForConnect                    : false
         canOverlapSend                         : false
     h245Tunneling                              : true
     h245Control                                :
       h245Control - Sequence[ 0 ]              :

       H245 MultimediaSystemControlMessage      :
         request                                :
           terminalCapabilitySet                :
             sequenceNumber                     : 1
             protocolIdentifer                  : itu-t


Agrawal, et al.                                              [Page 77]


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                                                : recommendation
                                                : h
                                                : 245
                                                : version
                                                : 3
             multiplexCapability                :
               h2250Capability                  :
                 maximumAudioDelayJitter        : 60
                 receiveMultipointCapability                 :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 transmitMultipointCapability                :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 receiveAndTransmitMultipointCapability      :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 mcCapability                                :
                   centralizedConferenceMC                   : false
                   deCentralizedConferenceMC                 : false
                 rtcpVideoControlCapability                  : false
                 mediaPacketizationCapability                :
                   h261aVideoPacketization                   : false
             capabilityTable                                 :
               capabilityTableEntryNumber                    : 7111
               capability                                    :
                 receiveAudioCapability                      :
                   g711Ulaw-64k                              : 60
               capabilityTableEntryNumber                    : 7110
               capability                                    :
                 receiveAudioCapability                      :
                   g711Alaw64k                               : 60
               capabilityTableEntryNumber                    : 728

Agrawal, et al.                                              [Page 78]


Internet Draft         SIP-H.323 Interworking               July 2001


               capability                                    :
                 receiveAudioCapability                      :
                   g728                                      : 60
               capabilityTableEntryNumber                    : 261
               capability                                :
                 receiveVideoCapability                  :
                   h261VideoCapability                   :
                     qcifMPI                             : 1 [1/29.97
                                                            Hz]
                     cifMPI                              : 1 [1/29.97
                                                            Hz]
                     temporalSpatialTradeOffCapability   : false
                     maxBitRate                          : 600 [100
                                                           bit/sec]
                     stillImageTransmission              : false
               capabilityTableEntryNumber                : 263
               capability                                :
                 receiveVideoCapability                  :
                   h263VideoCapability                   :
                     sqcifMPI                            : 1 [1/29.97
                                                            Hz]
                     qcifMPI                             : 1 [1/29.97
                                                            Hz]
                     cifMPI                              : 1 [1/29.97
                                                            Hz]
                     maxBitRate                          : 1000 [100
                                                            bit/s]
                     unrestrictedVector                      : false
                     arithmeticCoding                        : false
                     advancedPrediction                      : false
                     pbFrames                                : false
                     temporalSpatialTradeOffCapability       : false
                     errorCompensation                       : false
               capabilityTableEntryNumber                    : 7231
               capability                                    :
                 receiveAudioCapability                      :
                   g7231                                     :
                     maxA1-sduAudioFrames                    : 8
                     silenceSuppression                      : false
               capabilityTableEntryNumber                    : 120
               capability                                    :
                 receiveAndTransmitDataApplicationCapability :
                   application                               :
                     t120                                    :
                       separateLANStack                      :
                   maxBitRate                                : 1000
                                                               [100
                                                               bit/s]
             capabilityDescriptors                           :
               capabilityDescriptorNumber                    : 0
               simultaneousCapabilities                      : 7111
                                                               7110
                                                               7231
                                                               728

Agrawal, et al.                                              [Page 79]


Internet Draft         SIP-H.323 Interworking               July 2001


                                                             : 261 263
                                                             : 120
                                                             :
       h245Control - Sequence[ 1 ]                           :
       H245 MultimediaSystemControlMessage                   :
         request                                             :
           masterSlaveDetermination                          :
             terminalType                                    : 50
             statusDeterminationNumber                       : 10712223

}


F2 INVITE IWF -> SIP

INVITE sip:UserB@there.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Contact: <sip:UserA19284@164.164.28.121>
Content-Length: 0


F3 180 Ringing SIP -> IWF

SIP/2.0 100 Trying
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Content-Length: 0


F4 Alerting IWF -> H.323

H323-UserInformation
{
   h323-uu-pdu                                               :
     h323-message-body                                       :
       alerting                                              :
         protocolIdentifier                                  : itu-t
                                                             :
recommendation
                                                             : h
                                                             : 2250
                                                             : version
                                                             : 2
         destinationInfo                                     : gateway
         callIdentifier                           : Hex( 56 34 34 34 34
EF 09
00 21 21 E4 83 2D 7E BA AB )
}
Agrawal, et al.                                              [Page 80]


Internet Draft         SIP-H.323 Interworking               July 2001


F5 200 OK SIP -> IWF

SIP/2.0 200 OK
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F6 Connect IWF -> H.323


Connect (MSD Ack, TCS Ack, TCS)

H323-UserInformation
{
   h323-uu-pdu                               :
     h323-message-body                       :
       connect                               :
         protocolIdentifier                  : itu-t
                                             : recommendation
                                             : h
                                             : 2250
                                             : version
                                             : 2
         h245Address                         :
           ipAddress                         :
             ip                              : 164.164.28.141
             port                            : 2002
         destinationInfo                     :
           vendor                            :
             vendor                          :
               t32CountryCode                : 11
               t32Extension                  : 11
               manufacturerCode              : 11
               productId                     : IWF
               versionId                     : SIP-H323
           gateway                           :
           mc                                : false
           undefinedNode                     : false
         conferenceID                        : Hex( 56 34 34 34 34 EF
                                               09 00 21

Agrawal, et al.                                              [Page 81]


Internet Draft         SIP-H.323 Interworking               July 2001


                                               21 E4 83 2D 7E BA AB )
         callIdentifier                      :
           guid                              : Hex( 56 34 34 34 34 EF
                                               08 00 21
                                               21 E4 83 2D 7E BA AB )
     h245Tunneling                           : true

     h245Control                                             :
       h245Control - Sequence[ 0 ]                           :

       H245 MultimediaSystemControlMessage
       {
         response                                            :
                masterSlaveDeterminationAck                  :
                decision                                     : master
       }
                                                             :
       h245Control - Sequence[ 1 ]                           :

       H245 MultimediaSystemControlMessage
       {
            response                                         :
              terminalCapabilitySetAck                       :
                sequenceNumber                               : 1
       }

       h245Control - Sequence[ 2 ]

       H245 MultimediaSystemControlMessage                   :
         request                                             :
           terminalCapabilitySet                  :
             sequenceNumber                       : 1
             protocolIdentifer                    : itu-t
                                                  : recommendation
                                                  : h
                                                  : 245
                                                  : version
                                                  : 3
             multiplexCapability                             :
               h2250Capability                               :
                 maximumAudioDelayJitter                     : 60
                 receiveMultipointCapability                 :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 transmitMultipointCapability                :
                   multicastCapability                       : false
                   multiUniCastConference                    : false

Agrawal, et al.                                              [Page 82]


Internet Draft         SIP-H.323 Interworking               July 2001


                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 receiveAndTransmitMultipointCapability      :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 mcCapability                                :
                   centralizedConferenceMC                   : false
                   deCentralizedConferenceMC                 : false
                 rtcpVideoControlCapability                  : false
                 mediaPacketizationCapability                :
                   h261aVideoPacketization                   : false
             capabilityTable                                 :
               capabilityTableEntryNumber                    : 7111
               capability                                    :
                 receiveAudioCapability                      :
                   g711Ulaw-64k                              : 60

             capabilityDescriptors                           :
               capabilityDescriptorNumber                    : 0
               simultaneousCapabilities                      : 7111
}

F7 Facility H.323 -> IWF

Facility (TCS Ack, MSD Ack, OLC)

H323-UserInformation
{
   h323-uu-pdu                               :
     h323-message-body                       :
       facility                              :
         protocolIdentifier                  : itu-t
                                             : recommendation
                                             : h
                                             : 2250
                                             : version
                                             : 2
         reason                              :
         callIdentifier                      :
           guid                              : Hex( 56 34 34 34 34 EF
                                               08 00 21
                                               21 E4 83 2D 7E BA AB )

Agrawal, et al.                                              [Page 83]


Internet Draft         SIP-H.323 Interworking               July 2001


     h245Tunneling                           : true
     h245Control                             :
       h245Control - Sequence[ 0 ]           :

       H245 MultimediaSystemControlMessage
       {
         response                            :
           terminalCapabilitySetAck          :
             sequenceNumber                  : 1
       }

       h245Control - Sequence[ 1 ]           :
       H245 MultimediaSystemControlMessage
       {
         response                            :
           masterSlaveDeterminationAck       :
             decision                        : slave

       h245Control - Sequence[ 2 ]      :
       H245 MultimediaSystemControlMessage
       {
         request                             :
           openLogicalChannel                :
             forwardLogicalChannelNumber     : 1
             forwardLogicalChannelParameters :
               dataType                      :
                 audioData                   :
                   g711Ulaw-64k              : 60
               multiplexParameters           :
               h2250LogicalChannelParameters :
                 sessionID                   : 1
                 mediaControlChannel         :
                   unicastAddress            :
                     iPAddress               :
                       network               : 164.164.28.101
                       tsapIdentifier        : 2327
       }

}



F8 Facility  IWF -> H323

 Facility (OLC Ack, OLC)

H323-UserInformation
{
   h323-uu-pdu                               :
     h323-message-body                       :
       facility                              :
         protocolIdentifier                  : itu-t
                                             : recommendation
                                             : h

Agrawal, et al.                                              [Page 84]


Internet Draft         SIP-H.323 Interworking               July 2001

                                             : 2250
                                             : version
                                             : 2
         reason                              :
         callIdentifier                      :
           guid                              : Hex( 56 34 34 34 34 EF
                                               08 00 21
                                               21 E4 83 2D 7E BA AB )
     h245Tunneling                           : true
     h245Control                             :
       h245Control - Sequence[ 0 ]           :

       H245 MultimediaSystemControlMessage
       {
         response                                         :
           openLogicalChannelAck                          :
             forwardLogicalChannelNumber                  : 1
             forwardMultiplexAckParameters                :
               h2250LogicalChannelAckParameters           :
                 sessionID                                : 1
                 mediaChannel                             :
                   unicastAddress                  :
                     iPAddress                     :
                       network                     : 164.164.28.141
                       tsapIdentifier              : 4326
                 mediaControlChannel               :
                   unicastAddress                  :
                     iPAddress                     :
                       network                     : 164.164.28.141
                       tsapIdentifier                     : 4327
                 flowControlToZero                        : true
       }

       h245Control - Sequence[ 1 ]           :
       H245 MultimediaSystemControlMessage
       {
         request                             :
           openLogicalChannel                :
             forwardLogicalChannelNumber     : 1
             forwardLogicalChannelParameters :
               dataType                      :
                 audioData                   :
                   g711Ulaw-64k              : 60
               multiplexParameters           :
               h2250LogicalChannelParameters :
                 sessionID                   : 1
                 mediaControlChannel         :
                   unicastAddress            :
                     iPAddress               :
                       network               : 164.164.28.141
                       tsapIdentifier        : 4327
       }

}


Agrawal, et al.                                              [Page 85]


Internet Draft         SIP-H.323 Interworking               July 2001


F9 Facility H323 -> IWF
 Facility (OLC Ack)

H323-UserInformation
{
   h323-uu-pdu                               :
     h323-message-body                       :
       facility                              :
         protocolIdentifier                  : itu-t
                                             : recommendation
                                             : h
                                             : 2250
                                             : version
                                             : 2
         reason                              :
         callIdentifier                      :
           guid                              : Hex( 56 34 34 34 34 EF
                                               08 00 21
                                               21 E4 83 2D 7E BA AB )
     h245Tunneling                           : true
     h245Control                             :
       h245Control - Sequence[ 0 ]           :

       H245 MultimediaSystemControlMessage
       {
         response                                         :
           openLogicalChannelAck                          :
             forwardLogicalChannelNumber                  : 1
             forwardMultiplexAckParameters                :
               h2250LogicalChannelAckParameters           :
                 sessionID                                : 1
                 mediaChannel                             :
                   unicastAddress              :
                     iPAddress                 :
                       network                 : 164.164.28.121
                       tsapIdentifier          : 2326
                 mediaControlChannel           :
                   unicastAddress              :
                     iPAddress                 :
                       network                 : 164.164.28.121
                       tsapIdentifier          : 2327
                 flowControlToZero             : true
       }
}



F10 ACK IWF -> SIP

ACK sip:UserB@there.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876


Agrawal, et al.                                              [Page 86]


Internet Draft         SIP-H.323 Interworking               July 2001

Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 ACK
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserA 2890844526 2890844526 IN IP4 164.164.28.101
s=-
c=IN IP4 164.164.28.101
t=3034423619 0
m=audio 2326 RTP/AVP 0
a=rtpmap:0 PCMU/8000



---------------------------------------------------------------

C.3 Call from H.323 terminal to SIP terminal using fast connect
procedure.


Message Details
---------------

F1 Setup (fastStart=true,OLC) H323 -> IWF

H323-UserInformation
{
   h323-uu-pdu                                       :
     h323-message-body                               :
       setup                                         :
         protocolIdentifier                          : itu-t
                                                     : recommendation
                                                     : h
                                                     : 2250
                                                     : version
                                                     : 2
         h245Address                                 :
           ipAddress                                 :
             ip                                      : 164.164.28.101
             port                                    : 2000
         sourceAddress                               :
           e164 address                           : 01000220013101720
           h323-ID address                        : UserB@there.com
           e164 address                           : 7199557429
         sourceInfo                                  :
           vendor                                    :
             vendor                                  :
               t32CountryCode                        : 11
               t32Extension                          : 11
               manufacturerCode                      : 11
               productId                             : IWF
               versionId                             : SIP-H323
           terminal                                  :
           mc                                        : false

Agrawal, et al.                                              [Page 87]


Internet Draft         SIP-H.323 Interworking               July 2001


           undefinedNode                             : false
         destCallSignalAddress                       :
           ipAddress                                 :
             ip                                      : 164.164.28.121
             port                                    : 1720
         activeMC                                    : false
         conferenceID                                : Hex( 56 34 34 34
                                                       34 EF 0B 00 21
                                                       21 E4 A5 35 A3
                                                       9A 82)
         conferenceGoal                              : create
         callType                                    : pointToPoint
         sourceCallSignalAddress                     :
           ipAddress                                 :
             ip                               : 164.164.28.101
             port                             : 1700
         callIdentifier                       :
           guid                               : Hex( 56 34 34 34 34 EF
                                                  0A 00 21 21 E4 A5 35
                                                  A3 9A 82 )
         fastStart                            :
           fastStart - Sequence[ 0 ]          :
           forwardLogicalChannelNumber        : 1
           forwardLogicalChannelParameters    :
             dataType                         :
               audioData                             :
                 g711Ulaw-64k                        : 60
             multiplexParameters                     :
             h2250LogicalChannelParameters           :
               sessionID                             : 1
               mediaControlChannel                   :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2327
                                                     :
           fastStart - Sequence[ 1 ]                 :
           forwardLogicalChannelNumber               : 2
           forwardLogicalChannelParameters           :
             dataType                                :
               audioData                             :
                 g7231                               :
                   maxA1-sduAudioFrames              : 8
                   silenceSuppression                : false
             multiplexParameters                     :
             h2250LogicalChannelParameters           :
               sessionID                             : 1
               mediaControlChannel                   :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2327
                                                     :
           fastStart - Sequence[ 2 ]                 :

Agrawal, et al.                                              [Page 88]


Internet Draft         SIP-H.323 Interworking               July 2001


           forwardLogicalChannelNumber               : 4762
           forwardLogicalChannelParameters           :
             dataType                                :
               nullData                              :
             multiplexParameters                     :
               none                                  :
           reverseLogicalChannelParameters           :
             dataType                                :
               audioData                             :
                 g711Ulaw-64k                        : 60
             multiplexParameters                     :
             h2250LogicalChannelParameters           :
               sessionID                             : 1
               mediaChannel                          :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2326
               mediaControlChannel                   :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2327
                                                     :
           fastStart - Sequence[ 3 ]                 :
           forwardLogicalChannelNumber               : 4762
           forwardLogicalChannelParameters           :
             dataType                                :
               nullData                              :
             multiplexParameters                     :
               none                                  :
           reverseLogicalChannelParameters           :
             dataType                                :
               audioData                             :
                 g7231                               :
                   maxA1-sduAudioFrames              : 8
                   silenceSuppression                : false
             multiplexParameters                     :
             h2250LogicalChannelParameters           :
               sessionID                             : 1
               mediaChannel                          :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2326
               mediaControlChannel                   :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2327
                                                     :
           fastStart - Sequence[ 4 ]                 :
           forwardLogicalChannelNumber               : 3
           forwardLogicalChannelParameters           :

Agrawal, et al.                                              [Page 89]


Internet Draft         SIP-H.323 Interworking               July 2001


             dataType                                :
               videoData                             :
                 h261VideoCapability                 :
                   qcifMPI                           : 1 [1/29.97 Hz]
                   cifMPI                            : 1 [1/29.97 Hz]
                   temporalSpatialTradeOffCapability : false
                   maxBitRate                        : 600 [100
                                                       bit/sec]
                   stillImageTransmission            : false
             multiplexParameters                     :
             h2250LogicalChannelParameters           :
               sessionID                             : 2
               mediaControlChannel                   :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2329
                                                     :
           fastStart - Sequence[ 5 ]                 :
           forwardLogicalChannelNumber               : 4762
           forwardLogicalChannelParameters           :
             dataType                                :
               nullData                              :
             multiplexParameters                     :
               none                                  :
           reverseLogicalChannelParameters           :
             dataType                                :
               videoData                             :
                 h261VideoCapability                 :
                   qcifMPI                           : 1 [1/29.97 Hz]
                   cifMPI                            : 1 [1/29.97 Hz]
                   temporalSpatialTradeOffCapability : false
                   maxBitRate                        : 600 [100
                                                       bit/sec]
                   stillImageTransmission            : false
             multiplexParameters                     :
             h2250LogicalChannelParameters           :
               sessionID                             : 2
               mediaChannel                          :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2328
               mediaControlChannel                   :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.101
                     tsapIdentifier                  : 2329
                                                     :
         mediaWaitForConnect                         : false
         canOverlapSend                              : false
     h245Tunneling                                   : false
}


Agrawal, et al.                                              [Page 90]


Internet Draft         SIP-H.323 Interworking               July 2001



F2 INVITE IWF -> SIP

INVITE sip:UserB@there.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Contact: <sip:UserA19284@164.164.28.121>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserA 2890844526 2890844526 IN IP4 164.164.28.101
s=-
c=IN IP4 164.164.28.101
t=3034423619 0
m=audio 2326 RTP/AVP 0
a=rtpmap:0 PCMU/8000



F3 180 RINGING SIP -> IWF

SIP/2.0 100 Trying
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Content-Length: 0



F4 Alerting IWF -> H323

H323-UserInformation
{
   h323-uu-pdu                                               :
     h323-message-body                                       :
       alerting                                              :
         protocolIdentifier                                  : itu-t
                                                             :
recommendation
                                                             : h
                                                             : 2250
                                                             : version
                                                             : 2
         destinationInfo                                     : gateway
         callIdentifier                           : Hex( 56 34 34 34 34
                                                    EF 0A 00 21 21 E4
                                                    A5 35 A3 9A 82 )
}

Agrawal, et al.                                              [Page 91]


Internet Draft         SIP-H.323 Interworking               July 2001


F5 200 OK  SIP -> IWF

SIP/2.0 200 OK
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F6 Connect (fastStart=true,OLC) IWF -> H323

H323-UserInformation
{
   h323-uu-pdu                                       :
     h323-message-body                               :
       connect                                       :
         protocolIdentifier                          : itu-t
                                                     : recommendation
                                                     : h
                                                     : 2250
                                                     : version
                                                     : 2
         destinationInfo                             :
           vendor                                    :
             vendor                                  :
               t32CountryCode                        : 11
               t32Extension                          : 11
               manufacturerCode                      : 11
               productId                             : IWF
               versionId                             : SIP-H323
           gateway                              :
           mc                                   : false
           undefinedNode                        : false
         conferenceID                           : Hex( 56 34 34 34 34
                                                  EF 0B 00 21 21 E4 A5
                                                  35 A3 9A 82 )
         callIdentifier                         :
           guid                                 : Hex( 56 34 34 34 34
                                                  EF 0A 00 21 21 E4 A5
                                                  35 A3 9A 82 )
         fastStart                              :
           fastStart - Sequence[ 0 ]                 :

Agrawal, et al.                                              [Page 92]


Internet Draft         SIP-H.323 Interworking               July 2001


           forwardLogicalChannelNumber               : 1
           forwardLogicalChannelParameters           :
             dataType                                :
               audioData                             :
                 g711Ulaw-64k                        : 60
             multiplexParameters                     :
             h2250LogicalChannelParameters           :
               sessionID                             : 1
               mediaChannel                          :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.141
                     tsapIdentifier                  : 4326
               mediaControlChannel                   :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.141
                     tsapIdentifier                  : 4327
                                                     :
           fastStart - Sequence[ 1 ]                 :
           forwardLogicalChannelNumber               : 1
           forwardLogicalChannelParameters           :
             dataType                                :
               nullData                              :
             multiplexParameters                     :
               none                                  :
           reverseLogicalChannelParameters           :
             dataType                                :
               audioData                             :
                 g711Ulaw-64k                        : 60
             multiplexParameters                     :
             h2250LogicalChannelParameters           :
               sessionID                             : 1
               mediaControlChannel                   :
                 unicastAddress                      :
                   iPAddress                         :
                     network                         : 164.164.28.141
                     tsapIdentifier                  : 4327
                                                     :

                                                     :
     h245Tunneling                                   : false
}


F7 Ack IWF -> SIP

ACK sip:UserB@there.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:UserB@there.com>;tag=9876
Call-ID: 4423493498581@164.164.28.121
CSeq: 1024 ACK
Content-Length: 0

Agrawal, et al.                                              [Page 93]


Internet Draft         SIP-H.323 Interworking               July 2001



---------------------------------------------------------

C.4  Call from H.323 terminal to SIP terminal using overlapped
sending.


Message Details.

F1 Setup H.323 -> IWF

Setup(CanOverlapSend=True, CgPn=555-1212, CdPn=214-555-1313)

H323-UserInformation
{
   h323-uu-pdu                                               :
     h323-message-body                                       :
       setup                                                 :
         protocolIdentifier                                  : itu-t
                                                             :
recommendation
                                                             : h
                                                             : 2250
                                                             : version
                                                             : 2
         sourceAddress                             :
           e164 address                            : 01000220013101720
           h323-ID address                         : UserA19284
           e164 address                            : 7199557429
         sourceInfo                                          :
           vendor                                            :
             vendor                                          :
               t32CountryCode                                : 11
               t32Extension                                  : 11
               manufacturerCode                              : 11
               productId                                     : IWF
               versionId                                     : SIP-H323
           terminal                                          :
           mc                                                : false
           undefinedNode                                     : false
         destinationAddress                          :
           e164 address                              : 555-1212
         destCallSignalAddress                       :
           ipAddress                                 :
             ip                                      : 164.164.28.121
             port                                            : 1720
         activeMC                                            : false
         conferenceID                                : Hex( 56 34 34 34
                                                       34 EF 09 00 21
                                                       21 E4 83 2D 7E
                                                       BA AB )
         conferenceGoal                              : create
         callType                                    : pointToPoint
         sourceCallSignalAddress                     :

Agrawal, et al.                                              [Page 94]


Internet Draft         SIP-H.323 Interworking               July 2001


           ipAddress                                 :
             ip                                      : 164.164.28.101
             port                                    : 3472
         callIdentifier                              :
           guid                                      : Hex( 56 34 34 34
                                                       34 EF 08 00 21
                                                       21 E4 83 2D 7E
                                                       BA AB )
         mediaWaitForConnect                         : false
         canOverlapSend                              : true
     h245Tunneling                                   : false
}


F2 Setup Ack IWF -> H.323

Setup Ack
{
   Protocol Identifier                          : itu-t
                                                : recommendation
                                                : h
                                                : 2250
                                                : version
                                                : 2
   callIdentifier                               :
           guid                                 : Hex( 56 34 34 34
                                                  34 EF 08 00 21 21 E4
                                                  83 2D 7E BA AB )
   Message type                                 : 11011 (Bits)
   Progress indicator                           : 0001000   (Octet 4)
}




F3 INVITE IWF -> SIP

INVITE sip:555-1212@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:555-1212@164.164.28.121>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1 INVITE
Contact: <sip:UserA19284@164.164.28.121>
Content-Length: 0


F4 484 Address Incomplete SIP -> IWF

SIP/2.0 484 Address Incomplete
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:555-1212@164.164.28.121>;tag=34239188
Call-ID: 4423493498581@164.164.28.121

Agrawal, et al.                                              [Page 95]


Internet Draft         SIP-H.323 Interworking               July 2001


CSeq: 1 INVITE
Content-Length: 0


F5 ACK IWF -> SIP

ACK sip:555-1212@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:555-1212@164.164.28.121>;tag=34239188
Call-ID: 4423493498581@164.164.28.121
CSeq: 1 ACK
Content-Length: 0


F6 Information H.323 -> IWF

Information (CdPn=972-555-1212)

H323-UserInformation
{
   h323-uu-pdu                                               :
     h323-message-body                                       :
       information                                           :
         protocolIdentifier                                  : itu-t
                                                             : recommendation
                                                             : h
                                                             : 2250
                                                             : version
                                              : 2
         callIdentifier                       :
           guid                               : Hex( 56 34 34 34 34 EF
                                                08 00 21 21 E4 83 2D 7E
                                                BA AB )
}


F7 INVITE IWF -> SIP

INVITE sip:+1-972-555-1212@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:+1-972-555-1212@164.164.28.121>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1 INVITE
Contact: <sip:UserA19284@164.164.28.121>
Content-Length: 0


F8 180 Ringing SIP -> IWF

SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>

Agrawal, et al.                                              [Page 96]


Internet Draft         SIP-H.323 Interworking               July 2001


To: <sip:+1-972-555-1212@164.164.28.121>;tag=843423
Call-ID: 4423493498581@164.164.28.121
CSeq: 1 INVITE
Content-Length: 0


F9 Alerting IWF -> H.323

H323-UserInformation
{
   h323-uu-pdu                                               :
     h323-message-body                                       :
       alerting                                              :
         protocolIdentifier                                  : itu-t
                                                             :
recommendation
                                                             : h
                                                             : 2250
                                                             : version
                                                             : 2
         destinationInfo                                     : gateway
         callIdentifier                           : Hex( 56 34 34 34 34
                                                    EF 0A 00 21 21 E4
                                                    A5 35 A3 9A 82 )
}



F10 200 OK SIP -> IWF

SIP/2.0 200 OK
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:+1-972-555-1212@164.164.28.121>;tag=843423
Call-ID: 4423493498581@164.164.28.121
CSeq: 1 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F11 Connect IWF -> H.323

Connect



Agrawal, et al.                                              [Page 97]


Internet Draft         SIP-H.323 Interworking               July 2001



H323-UserInformation
{
   h323-uu-pdu                                               :
     h323-message-body                                       :
       callproceeding                                        :
         protocolIdentifier                                  : itu-t
                                                             :
recommendation
                                                             : h
                                                             : 2250
                                                             : version
                                                             : 2
         h245Address                              :
           ipAddress                              :
             ip                                   : 164.164.28.141
             port                                 : 2000
         destinationInfo                          : gateway
      conferenceID                                : Hex( 56 34 34 34 34
                                                    EF 09 00 21 21 E4
                                                    83 2D 7E BA AB )
         callIdentifier                           : Hex( 56 34 34 34 34
                                                    EF 09 00 21 21 E4
                                                    83 2D 7E BA AB )
}



F12 H245 H.323 <-> IWF

H245


F13 ACK IWF -> SIP

ACK sip:+1-972-555-1212@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
From: <sip:UserA19284@164.164.28.121>
To: <sip:+1-972-555-1212@164.164.28.121>
Call-ID: 4423493498581@164.164.28.121
CSeq: 1 ACK
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserA 2890844526 2890844526 IN IP4 164.164.28.101
s=-
c=IN IP4 164.164.28.101
t=3034423619 0
m=audio 2326 RTP/AVP 0
a=rtpmap:0 PCMU/8000

---------------------------------------------------------------------


Agrawal, et al.                                              [Page 98]


Internet Draft         SIP-H.323 Interworking               July 2001


C.4  Simple call from SIP terminal to H.323 terminal.

Message Details

F1 INVITE SIP -> IWF

INVITE sip:UserA@here.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:UserA@here.com>
From: <sip:UserB@there.com>
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F2 Setup IWF -> H.323

Setup

H323-UserInformation
{
   h323-uu-pdu                                  :
     h323-message-body                          :
       setup                                    :
         protocolIdentifier                     : itu-t
                                                : recommendation
                                                : h
                                                : 2250
                                                : version
                                                : 2
         sourceInfo                             : gateway
         sourceAddress                          :
           e164 address                         : 01000220013101720
           h323-ID address                      : UserB@there.com
           e164 address                         : 7199557429
         sourceInfo                             :
           vendor                               :
             vendor                             :
               t32CountryCode                   : 11
               t32Extension                     : 11
               manufacturerCode                 : 11
               productId                        : IWF
               versionId                        : SIP-H323
           terminal                             :

Agrawal, et al.                                              [Page 99]


Internet Draft         SIP-H.323 Interworking               July 2001


           mc                                   : false
           undefinedNode                        : false
         destinationAddress                     :
           h323-ID Address                      : UserA@here.com
         destCallSignalAddress                  :
           ipAddress                            :
             ip                                 : 164.164.28.141
             port                               : 1720
         activeMC                               : false
         conferenceID                           : Hex( 56 34 34 34
                                                  34 EF 09 00 21 21 E4
                                                  83 2D 7E BA AB )
         conferenceGoal                         : create
         callType                               : pointToPoint
         sourceCallSignalAddress                :
           ipAddress                            :
             ip                                 : 164.164.28.101
             port                               : 3472
         callIdentifier                         :
           guid                                 : Hex( 56 34 34 34
                                                  34 EF 08 00 21 21 E4
                                                  83 2D 7E BA AB )
         mediaWaitForConnect                    : false
         canOverlapSend                         : false
     h245Tunneling                              : false
}


F3 Alerting H.323 -> IWF

H323-UserInformation
{
   h323-uu-pdu                                   :
     h323-message-body                           :
       alerting                                  :
         protocolIdentifier                      : itu-t
                                                 : recommendation
                                                 : h
                                                 : 2250
                                                 : version
                                                 : 2
         destinationInfo                         : terminal
         callIdentifier                          : Hex( 56 34 34 34 34
                                                   EF 08 00 21 21 E4 83
                                                   2D 7E BA AB )
}

F4 180 Ringing IWF -> SIP

SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:UserA@here.com>
From: <sip:UserB@there.com>;tag=a563s1


Agrawal, et al.                                              [Page 100]


Internet Draft         SIP-H.323 Interworking               July 2001


Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Content-Length: 0


F5 Connect H.323 -> IWF

H323-UserInformation
{
   h323-uu-pdu                                     :
     h323-message-body                             :
       callproceeding                              :
         protocolIdentifier                        : itu-t
                                                   : recommendation
                                                   : h
                                                   : 2250
                                                   : version
                                                   : 2
         h245Address                               :
           ipAddress                               :
             ip                                    : 164.164.28.141
             port                                  : 2000
         destinationInfo                           : terminal
      conferenceID                                 : Hex( 56 34 34 34
                                                     34 EF 09 00 21 21
                                                     E4 83 2D 7E BA AB)
         callIdentifier                            : Hex( 56 34 34 34
                                                     34 EF 09 00 21 21
                                                     E4 83 2D 7E BA AB)
}



F6 H.245 IWF <-> H.323

H.245


F7 200 OK IWF -> SIP

SIP/2.0 200 OK
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:UserA@here.com>
From: <sip:UserB@there.com>;tag=a563s1
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Contact: <sip:UserA876665@164.164.28.121>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserA 2890844526 2890844526 IN IP4 164.164.28.101
s=-
c=IN IP4 164.164.28.101

Agrawal, et al.                                              [Page 101]


Internet Draft         SIP-H.323 Interworking               July 2001


t=3034423619 0
m=audio 2326 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F8 ACK SIP -> IWF

ACK sip:UserA876665@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:UserA@here.com>
From: <sip:UserB@there.com>;tag=a563s1
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 ACK
Content-Length: 0
-----------------------------------------------------------

C.5 Call from SIP terminal to H.323 terminal using H.245 tunneling.

Message Details

F1  INVITE SIP -> IWF

INVITE sip:UserA@here.com SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:UserA@here.com>
From: <sip:UserB@there.com>
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F2 Setup(tunn.=true,TCS,MSD) IWF -> H323

H323-UserInformation
{
   h323-uu-pdu                                               :
     h323-message-body                                       :
       setup                                                 :
         protocolIdentifier                          : itu-t
                                                     : recommendation
                                                     : h
                                                     : 2250
                                                     : version
                                                     : 2

Agrawal, et al.                                              [Page 102]


Internet Draft         SIP-H.323 Interworking               July 2001


         h245Address                                 :
           ipAddress                                 :
             ip                                      : 164.164.28.101
             port                                    : 2000
         sourceAddress                               :
           e164 address                           : 01000220013101720
           h323-ID address                        : UserB@there.com
           e164 address                           : 7199557429
         sourceInfo                                          :
           vendor                                            :
             vendor                                          :
               t32CountryCode                                : 11
               t32Extension                                  : 11
               manufacturerCode                              : 11
               productId                                     : IWF
               versionId                                     : SIP-H323
           terminal                                          :
           mc                                                : false
           undefinedNode                                     : false
         destCallSignalAddress                               :
           ipAddress                              :
             ip                                   : 164.164.28.141
             port                                 : 1720
         activeMC                                 : false
         conferenceID                             : Hex( 56 34 34 34 34
                                                    EF 09 00 21 21 E4
                                                    83 2D 7E BA AB )
         conferenceGoal                           : create
         callType                                 : pointToPoint
         sourceCallSignalAddress                  :
           ipAddress                              :
             ip                                   : 164.164.28.121
             port                                 : 3472
         callIdentifier                           :
           guid                                   : Hex( 56 34 34 34
                                                    34 EF 08 00 21 21
                                                    E4 83 2D 7E BA AB )
         mediaWaitForConnect                      : false
         canOverlapSend                           : false
     h245Tunneling                                : true
     h245Control                                  :
       h245Control - Sequence[ 0 ]                :

       H245 MultimediaSystemControlMessage        :
         request                                  :
           terminalCapabilitySet                  :
             sequenceNumber                       : 1
             protocolIdentifer                    : itu-t
                                                  : recommendation
                                                  : h
                                                  : 245
                                                  : version
                                                  : 3
             multiplexCapability                  :

Agrawal, et al.                                              [Page 103]


Internet Draft         SIP-H.323 Interworking               July 2001


               h2250Capability                    :
                 maximumAudioDelayJitter                     : 60
                 receiveMultipointCapability                 :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 transmitMultipointCapability                :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 receiveAndTransmitMultipointCapability      :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 mcCapability                                :
                   centralizedConferenceMC                   : false
                   deCentralizedConferenceMC                 : false
                 rtcpVideoControlCapability                  : false
                 mediaPacketizationCapability                :
                   h261aVideoPacketization                   : false
             capabilityTable                                 :
               capabilityTableEntryNumber                    : 7111
               capability                                    :
                 receiveAudioCapability                      :
                   g711Ulaw-64k                              : 60
               capabilityTableEntryNumber                    : 7110
               capability                                    :
                 receiveAudioCapability                      :
                   g711Alaw64k                               : 60

             capabilityDescriptors                           :
               capabilityDescriptorNumber                    : 0
               simultaneousCapabilities                      : 7111
                                                             :
       h245Control - Sequence[ 1 ]                           :


Agrawal, et al.                                              [Page 104]


Internet Draft         SIP-H.323 Interworking               July 2001


       H245 MultimediaSystemControlMessage                   :
         request                                             :
           masterSlaveDetermination                          :
             terminalType                                    : 60
             statusDeterminationNumber                       : 10712223

}

F3 Alerting(tunn.=true,TCSAck,MSD Ack, TCS) H323 -> IWF

H323-UserInformation
{
   h323-uu-pdu                                               :
     h323-message-body                                       :
       alerting                                              :
         protocolIdentifier                   : itu-t
                                              : recommendation
                                              : h
                                              : 2250
                                              : version
                                              : 2
         destinationInfo                      : terminal
         callIdentifier                       : Hex( 56 34 34 34 34 EF
                                                08 00 21 21 E4 83 2D 7E
                                                BA AB )
     h245Tunneling                            : true
     h245Control                              :
       h245Control - Sequence[ 0 ]            :

       H245 MultimediaSystemControlMessage
       {
         response                             :
                masterSlaveDeterminationAck   :
                decision                      : slave
       }
                                                             :
       h245Control - Sequence[ 1 ]            :

       H245 MultimediaSystemControlMessage
       {
            response                          :
              terminalCapabilitySetAck        :
                sequenceNumber                : 1
       }

       h245Control - Sequence[ 2 ]

       H245 MultimediaSystemControlMessage    :
         request                              :
           terminalCapabilitySet              :
             sequenceNumber                   : 1
             protocolIdentifer                : itu-t
                                              : recommendation
                                              : h

Agrawal, et al.                                              [Page 105]


Internet Draft         SIP-H.323 Interworking               July 2001


                                              : 245
                                              : version
                                              : 3
             multiplexCapability              :
               h2250Capability                :
                 maximumAudioDelayJitter      : 60
                 receiveMultipointCapability  :
                   multicastCapability        : false
                   multiUniCastConference     : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 transmitMultipointCapability                :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 receiveAndTransmitMultipointCapability      :
                   multicastCapability                       : false
                   multiUniCastConference                    : false
                   mediaDistributionCapability               :
                     centralizedControl                      : false
                     distributedControl                      : false
                     centralizedAudio                        : false
                     distributedAudio                        : false
                     centralizedVideo                        : false
                     distributedVideo                        : false
                 mcCapability                                :
                   centralizedConferenceMC                   : false
                   deCentralizedConferenceMC                 : false
                 rtcpVideoControlCapability                  : false
                 mediaPacketizationCapability                :
                   h261aVideoPacketization                   : false
             capabilityTable                                 :
               capabilityTableEntryNumber                    : 7111
               capability                                    :
                 receiveAudioCapability                      :
                   g711Ulaw-64k                              : 60
               capabilityTableEntryNumber                    : 7110
               capability                                    :
                 receiveAudioCapability                      :
                   g711Alaw64k                               : 60
               capabilityTableEntryNumber                    : 728
               capability                                    :
                 receiveAudioCapability                      :

Agrawal, et al.                                              [Page 106]


Internet Draft         SIP-H.323 Interworking               July 2001


                   g728                                      : 60
               capabilityTableEntryNumber                    : 261
               capability                                    :
                 receiveVideoCapability                      :
                   h261VideoCapability                       :
                     qcifMPI                             : 1 [1/29.97
                                                            Hz]
                     cifMPI                              : 1 [1/29.97
                                                            Hz]
                     temporalSpatialTradeOffCapability   : false
                     maxBitRate                          : 600 [100
                                                            bit/sec]
                     stillImageTransmission              : false
               capabilityTableEntryNumber                : 263
               capability                                :
                 receiveVideoCapability                  :
                   h263VideoCapability                   :
                     sqcifMPI                            : 1 [1/29.97
                                                            Hz]
                     qcifMPI                             : 1 [1/29.97
                                                            Hz]
                     cifMPI                              : 1 [1/29.97
                                                            Hz]
                     maxBitRate                          : 1000 [100
                                                            bit/s]
                     unrestrictedVector                  : false
                     arithmeticCoding                    : false
                     advancedPrediction                  : false
                     pbFrames                            : false
                     temporalSpatialTradeOffCapability   : false
                     errorCompensation                   : false
               capabilityTableEntryNumber                : 7231
               capability                                :
                 receiveAudioCapability                      :
                   g7231                                     :
                     maxA1-sduAudioFrames                    : 8
                     silenceSuppression                      : false
               capabilityTableEntryNumber                    : 120
               capability                                    :
                 receiveAndTransmitDataApplicationCapability :
                   application                               :
                     t120                                    :
                       separateLANStack                  :
                   maxBitRate                            : 1000 [100
                                                            bit/s]
             capabilityDescriptors                       :
               capabilityDescriptorNumber                : 0
               simultaneousCapabilities                  : 7111 7110
                                                           7231 728
                                                         : 261 263
                                                         : 120
}



Agrawal, et al.                                              [Page 107]


Internet Draft         SIP-H.323 Interworking               July 2001


F4 180 Ringing IWF -> SIP

SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:UserA@here.com>
From: <sip:UserB@there.com>;tag=a563s1
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Content-Length: 0


F5 Facility(TCS Ack,OLC,MSD Ack) IWF -> H323

H323-UserInformation
{
   h323-uu-pdu                               :
     h323-message-body                       :
       facility                              :
         protocolIdentifier                  : itu-t
                                             : recommendation
                                             : h
                                             : 2250
                                             : version
                                             : 2
         reason                              :
         callIdentifier                      :
           guid                              : Hex( 56 34 34 34 34 EF
                                               08 00 21 21 E4 83 2D 7E
                                               BA AB )
     h245Tunneling                           : true
     h245Control                             :

       h245Control - Sequence[ 0 ]           :

       H245 MultimediaSystemControlMessage
       {
         response                            :
           terminalCapabilitySetAck          :
             sequenceNumber                  : 1
       }

       h245Control - Sequence[ 1 ]           :
       H245 MultimediaSystemControlMessage
       {
         response                            :
           masterSlaveDeterminationAck       :
             decision                        : master
       }

       h245Control - Sequence[ 2 ]      :
       H245 MultimediaSystemControlMessage
       {
         request                             :
           openLogicalChannel                :

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             forwardLogicalChannelNumber     : 1
             forwardLogicalChannelParameters :
               dataType                      :
                 audioData                   :
                   g711Ulaw-64k              : 60
               multiplexParameters           :
               h2250LogicalChannelParameters :
                 sessionID                   : 1
                 mediaControlChannel         :
                   unicastAddress            :
                     iPAddress               :
                       network               : 164.164.28.101
                       tsapIdentifier        : 2327
       }

}


F6 Facility (OLC Ack,OLC) H323 -> IWF

H323-UserInformation
{
   h323-uu-pdu                               :
     h323-message-body                       :
       facility                              :
         protocolIdentifier                  : itu-t
                                             : recommendation
                                             : h
                                             : 2250
                                             : version
                                             : 2
         reason                         :
         callIdentifier                      :
           guid                              : Hex( 56 34 34 34 34 EF
                                               08 00 21 21 E4 83 2D 7E
                                               BA AB )
     h245Tunneling                           : true
     h245Control                             :

       h245Control - Sequence[ 0 ]           :

       H245 MultimediaSystemControlMessage
       {
         response                                         :
           openLogicalChannelAck                          :
             forwardLogicalChannelNumber                  : 1
             forwardMultiplexAckParameters                :
               h2250LogicalChannelAckParameters           :
                 sessionID                                : 1
                 mediaChannel                             :
                   unicastAddress                         :
                     iPAddress                   :
                       network                   : 164.164.28.141
                       tsapIdentifier            : 4326

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                 mediaControlChannel             :
                   unicastAddress                :
                     iPAddress                   :
                       network                   : 164.164.28.141
                       tsapIdentifier            : 4327
                 flowControlToZero               : true
       }

       h245Control - Sequence[ 1 ]           :
       H245 MultimediaSystemControlMessage
       {
         request                             :
           openLogicalChannel                :
             forwardLogicalChannelNumber     : 1
             forwardLogicalChannelParameters :
               dataType                      :
                 audioData                   :
                   g711Ulaw-64k              : 60
               multiplexParameters           :
               h2250LogicalChannelParameters :
                 sessionID                   : 1
                 mediaControlChannel         :
                   unicastAddress            :
                     iPAddress               :
                       network               : 164.164.28.141
                       tsapIdentifier        : 4327
       }

}



F7 Facility (OLC Ack) IWF -> OLC

H323-UserInformation
{
   h323-uu-pdu                               :
     h323-message-body                       :
       facility                              :
         protocolIdentifier                  : itu-t
                                             : recommendation
                                             : h
                                             : 2250
                                             : version
                                             : 2
         reason                              :
         callIdentifier                      :
           guid                              : Hex( 56 34 34 34 34 EF
                                               08 00 21 21 E4 83 2D 7E
                                               BA AB )
     h245Tunneling                           : true
     h245Control                             :

       h245Control - Sequence[ 0 ]           :

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       H245 MultimediaSystemControlMessage
       {
         response                                         :
           openLogicalChannelAck                          :
             forwardLogicalChannelNumber                  : 1
             forwardMultiplexAckParameters                :
               h2250LogicalChannelAckParameters           :
                 sessionID                                : 1
                 mediaChannel                             :
                   unicastAddress               :
                     iPAddress                  :
                       network                  : 164.164.28.101
                       tsapIdentifier           : 2326
                 mediaControlChannel            :
                   unicastAddress               :
                     iPAddress                  :
                       network                  : 164.164.28.101
                       tsapIdentifier           : 2327
                 flowControlToZero              : true
       }
}



F8 Connect H323 -> IWF

H323-UserInformation
{
   h323-uu-pdu                               :
     h323-message-body                       :
       connect                               :
         protocolIdentifier                  : itu-t
                                             : recommendation
                                             : h
                                             : 2250
                                             : version
                                             : 2
         h245Address                         :
           ipAddress                         :
             ip                              : 164.164.28.141
             port                            : 2002
         destinationInfo                     :
           vendor                            :
             vendor                          :
               t32CountryCode                : 11
               t32Extension                  : 11
               manufacturerCode              : 11
               productId                     : IWF
               versionId                     : SIP-H323
           gateway                           :
           mc                                : false
           undefinedNode                     : false
         conferenceID                        : Hex( 56 34 34 34 34 EF

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                                               09 00 21 21 E4 83 2D 7E
                                               BA AB )
         callIdentifier                      :
           guid                              : Hex( 56 34 34 34 34 EF
                                               08 00 21 21 E4 83 2D 7E
                                               BA AB )
     h245Tunneling                           : true
}


F9 200 OK IWF -> SIP

SIP/2.0 200 OK
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:UserA@here.com>
From: <sip:UserB@there.com>;tag=a563s1
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Contact: <sip:UserA876665@164.164.28.121>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserA 2890844526 2890844526 IN IP4 164.164.28.101
s=-
c=IN IP4 164.164.28.101
t=3034423619 0
m=audio 2326 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F10 ACK SIP -> IWF

ACK sip:UserA876665@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:UserA@here.com>
From: <sip:UserB@there.com>;tag=a563s1
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 ACK
Content-Length: 0

--------------------------------------------------------------

C.6 Call from SIP terminal to H.323 terminal using overlapped
sending.


Message Details

F1 INVITE SIP -> IWF

INVITE sip:555-1212@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:555-1212@164.164.28.121>

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From: <sip:UserB@there.com>
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F2  Setup IWF -> H.323

H.225 Setup(canOverlapSend=true, incomplete address)


F3 484 Address Incomplete SIP -> IWF

SIP/2.0 484 Address Incomplete
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:555-1212@164.164.28.121>;tag=132328u439834234
From: <sip:UserB@there.com>
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Content-Length: 0


F4 ACK SIP -> IWF

ACK sip:555-1212@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:555-1212@164.164.28.121>;tag=132328u439834234
From: <sip:UserB@there.com>
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 ACK
Content-Length: 0


F5 Setup Ack  H.323 -> IWF

H.225 Setup Ack


F6 INVITE SIP -> IWF

INVITE sip:+1-972-555-1212@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:+1-972-555-1212@164.164.28.121>
From: <sip:UserB@there.com>

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Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Contact: <sip:UserB@there.com>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserB 2890844526 2890844526 IN IP4 164.164.28.141
s=-
c=IN IP4 164.164.28.141
t=3034423619 0
m=audio 4346 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F7 Information IWF -> H.323

H.225 Information (Additional Address)


F8 Alerting H.323 -> IWF

H.225 Alerting


F9 180 Ringing SIP -> IWF

SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:+1-972-555-1212@164.164.28.121>;tag=81902834
From: <sip:UserB@there.com>
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE
Content-Length: 0


F10 Connect H.323 -> IWF

H.225 Connect


F11 H245  H.323 <-> IWF

H.245 message exchange


F12 200 OK IWF -> SIP

SIP/2.0 200 OK
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:+1-972-555-1212@164.164.28.121>;tag=81902834
From: <sip:UserB@there.com>
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 INVITE

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Contact: <sip:+1-972-555-1212@164.164.28.121>
Content-Type: application/sdp
Content-Length: ...

v=0
o=UserA 2890844526 2890844526 IN IP4 164.164.28.101
s=-
c=IN IP4 164.164.28.101
t=3034423619 0
m=audio 2326 RTP/AVP 0
a=rtpmap:0 PCMU/8000


F13 ACK SIP -> IWF

ACK sip:+1-972-555-1212@164.164.28.121 SIP/2.0
Via: SIP/2.0/UDP 164.164.28.121:5060
To: <sip:+1-972-555-1212@164.164.28.121>;tag=81902834
From: <sip:UserB@there.com>
Call-ID: 56-23-12-12@164.164.28.141
CSeq: 1 ACK
Content-Length: 0



Appendix D : Summary of SIP-H.323 Interworking Requirements

This is the summary of the requirements mentioned in SIP-H.323
interworking draft [9] for basic call handling.

The Sip-H.323 requirements draft [9] provides the detail requirements
for SIP-H.323 Interworking based on H.323 Version 2 [5] and SIP RFC-
2543 [3]. There are two phases of the interworking standard. The first
phase will define the basic call establishment and termination.  The
second phase will include some optional, advanced features, and
services.  Both phases have to meet the general requirements specified
in the following sections.

A high-level summary of the requirements is described as stated below:

D.1. Functionality within the Interowkrking Function (IWF): The IWF may
have the look-up tables for SIP and H.323 address resolution. It may
contain the functions like Call sequence mapping, Address resolution,
Terminal Capability transactions, Opening and closing of media
channels, Mapping media algorithms for H.323 and SIP network, Call
resource reservation and release, Ability to provide the state of a
call, Call state machine, Mid Call signal processing, and Service
Interoperability Logic. No media processing will be done within the
IWF.

D.2. Pre-Call Requirements: The IWF shall support the address
resolution
schemes of both H.323 and SIP protocol and may register itself to the

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H.323 gatekeeper (GK) and the SIP server (Register, Redirect, Proxy).

D.3. General Interworking Requirements

D.3.1 Basic call Requirements

D.3.1.1 General Requirements: The default call parameters shall be
provided for the transaction along with resource release capability
with detection of the call deactivation.

D.3.1.2 Address Resolution: Both SIP and H.323 address resolution
services shall be provided for both SIP and H.323 calls.

D.3.1.3 Call with H.323 GKs: The addresses shall be resolved with the
help of the GK where the GK is present and will act as a SIP user agent
for registering with the H.323 GK.
D.3.1.4 Call with SIP Servers: The addresses shall be resolved with the
help of the SIP server where the SIP server is present and will act as
an H.323 terminal for registering with the SIP server.

D.3.1.5 Call with both H.323 GK and SIP Server: The IWF shall act both
SIP user agent and H.323 terminal.

D.3.1.6 Capability negotiation: It shall send all the capability
descriptors of H.323 and SDP descriptors of SIP in the best possible
way to each other without making any assumptions about the capabilities
of either SIP user agent or H.323 terminal. However, it may indicate a
default capability of H.323 terminal or SIP user agent even before
exchanging capability with H.323 (using H.245) and SIP (using SDP).
This default capability follows the mandatory capability requirements
as defined by the respective protocols.

D.3.1.7 Opening of logical channels: The IWF shall support
unidirectional, symmetric bi-directional, and asymmetric bi-directional
opening of channels, and will respond to the mode request and/or to the
request for reopening and changing an existing logical channel. The
support the flow control of H.323 shall also be provided.

D.3.1.8 Handling of Media transmission and reception: The IWF shall not
handle any RTP data.

D.3.2 Requirements for support of fast connect procedures: The IWF
shall shall support the fast Start element in H.323.

D.3.3 Requirements for support of H.245 tunnelling: The IWF shall
support the H.245 tunneling in the Setup message.

D.3.4 Requirements for support of pre granted ARQ: The IWF shall
support the pre-granted ARQ. In this case, it may do the address
resolution from H.323 GK using LRQ/LCF exchange.

D.3.5 Requirements for support of overlapped sending: The IWF shall
support the overlapped sending of dialed digits by using the INFO
method in SIP and Q.931 Setup, Setup Ack and Information Message in
H.323. The IWF shall support the transfer of digits during a call by

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using INFO method in SIP and UserInputIndication in H.245(H.323).

D.4. Transport: Both TCP and UDP shall be supported and the network
does not assure QoS. The signaling messages have not priority over
other messages. The Support for H.323Annex E (H.323 signaling over UDP)
is optional. RTP shall be used for carrying media over both SIP and
H.323 network.

D.5. Mapping between SIP and H.323

D.5.1 General Procedures: Call message sequence shall be maintained in
both directions. The messages that do not have a match on the other
side should be terminated on the IWF, and IWF should take the necessary
action on them. Information elements that are not in use on the H.323
side shall be generated by the IWF as required by the SIP protocol and
vice versa. The SIP data fields shall be converted into the
corresponding ASN.1 user-user information element structure. The user-
user information element structure shall be generated according to
specifications in Recommendation H.225.0 version 2.0 and H.245 version
4.0.

D.5.2 H.323 Call Signalling (H.225.0) and SIP Call Signalling

D.5.2.1. The IWF shall conform to the call signalling procedures
recommended for the SIP side independent of the H.323 side.

D.5.2.2. The IWF shall conform to the call signalling procedures
recommended for the H.323 side independent of the SIP side.

D.5.2.3. The IWF shall terminate the Q.931 Call Signalling Channel
between an H.323 endpoint or H.323 Gatekeeper (in case of GK routed
signalling) and the IWF on one hand and the call signalling (if any)
between the IWF and the SIP endpoint on the other side.

D.5.2.4. The IWF shall terminate the RAS Channel between H.323
Gatekeeper (if any) and IWF.

D.5.2.5. Messages for supplementary services (FACILITY, NOTIFY, and the
INFORMATION messages) in H.323 side may be processed by the IWF only if
the service is supported.

D.5.3 H.323 Call Control (H.245) and SIP Call Control (SDP): IWF should
try to map the H.245 and SDP to the maximum extent.

D.5.4 H.323 audio/video codec to SIP media formats: The IWF should
provide invisible support for all audio, video, and/or data algorithms
commonly supported by both ITU and IANA.

D.5.5 Call sequence: The call sequence on both sides should be
maintained in such a way that neither H.323 terminal nor SIP UA is
aware of the IWF presence. The IWF should provide seamless interworking
between the call flows of the two protocols. The IWF will not make any
modifications to the normal call flows of either protocols .The
messages and parameters which do not have direct mapping on the other

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side are to be generated by the IWF with default parameters in most
cases.

D.6. State Machine Requirements: Unexpected messages in a particular
state shall be treated as "Error" messages. All messages which do not
change the state shall be treated as "Non-triggering or Informational"
messages. All messages which expect a change in state shall be treated
as "Triggering" messages. For each state, there should be guidelines
that classify all possible messages into the above three categories.

D.7. Security: A simple security scheme should be enabled in the IWF.
In this scheme the IWF will accept requests from a pre-configured set
of SIP Server, SIP EP, H.323 EP, or H.323 GKs only and it will reject
all other requests.

References

[1] S. Bradner, "The Internet Standards Process -- Revision 3", BCP 9,
RFC 2026, October 1996.

[2] S. Bradner,"Key words for use in RFCs to indicate requirement
levels", RFC 2119,IETF, March 1997.

[3] M. Handley, H.Schulzrinne, E.Schooler, and J.Rosenberg,
"SIP:Session Initiation Prtocol", RFC 2543,IETF,March 1999.

[4] M. Handley and V. Jacobson, "SDP: Session Description Prtocol", RFC
2327, IETF, April 1998.

[5] "Packet based multimedia communication systems", Recommendation
H.323 Version 2,ITU-T,Geneva,Switzerland,Feb. 1998.

[6] J.Rosenberg and H.Salama, "Usage of TRIP in Gateways for Exporting
Phone Routes",draft-rs-trip-gw-00.txt, IETF, March 2000.  Work in
progress.

[7] S. Donovan, "The SIP INFO Method," RFC 2976, IETF, Oct.2000.

[8] Singh/Schulzrinne, "Interworking Between SIP/SDP and H.323", draft-
singh-sip-h323-00.txt,IETF, January 2000.  Work in progress.

[9]  H.Agrawal, R.R.Roy, V.Palawat, A.Johnston, C.Agboh, D.Wang,
K.Singh and H.Schulzrinne, "SIP-H.323 Interworking Requirements",draft-
agrawal-sip-h323-interworking-reqs-01.txt", IETF, Jan 2001. Work in
progress.

[10] H.Schulzrinne and S. Petrack, "RTP Payload for DTMF Digits,
Telephony Tones and Telephony Signals", RFC 2833, IETF, May 2000.

[11] G. Camarillo and A. Roach, "Best Current Practice for ISUP to SIP
mapping" Internet Draft, Work in Progress, March 2000.

[12] "Call Signaling Protocols and Media Stream Packetization for
Packet Based Multimedia Communications Systems " Recommendation H.225.0

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Version 2, ITU-T, Geneva, Switzerland, March 1997.

[13]  "Control protocol for multimedia communication, " Recommendation
H.245.0 Version 3, ITU-T, Geneva, Switzerland, Feb. 1998.



Acknowledgments


The authors would like to acknowledge the many contributors who debated
the SIP-H.323 interworking architecture and requirements on the IETF,
SIP and SG16 mailing lists. In particular, we would like to thank Dave
Walker (SS8 Networks) and Jean-Francois Mule(Clarent Corporation).
Contributions to this document have also been made through different
internet-drafts and discussions with members of SIP, H.323, aHIT!,
TIPHON and SG16 forums.



Authors' Addresses

        Hemant Agrawal
        Telverse Communications
        1010, Stewart Drive,
        Sunnyvale, CA - 94085
        USA
        Tel: +1 408 328 3421
        Fax: +1 408 617 0408
        Email: hagrawal@telverse.com

        Radhika R. Roy
        AT&T
        Room D3-2C09
        200 Laurel Avenue S.
        Middletown,
        NJ 07748,
        USA
        Tel: + 1-732-420-1580
        Fax: + 1-732-368-1302
        Email: rrroy@att.com


        Vipin Palawat
        Cisco Systems Inc.
        900, Chelmsford Street
        Tower II, Floor 14
        Lowell, MA  01851
        Tel: + 1-978-275-5122
        Fax: + 1-978-275-5122
        Email : vpalawat@cisco.com




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Internet Draft         SIP-H.323 Interworking               July 2001


        David Wang
        Nuera Communications Inc.
        10445 Pacific Center Court
        San Diego, CA 92121
        USA
        Tel:  + 1-858-625-9220 x 1260
        Fax:  + 1-858-625-2422
        Email: dwang@nuera.com

        Alan Johnston
        MCI WorldCom
        100 South Fourth Street
        St. Louis, MO 63102
        USA
        Tel:  + 1-314- 3427360
        Fax:  + 1-314-3428452
        Email: alan.johnston@wcom.com

        Charles Agboh
        Ebone
        Terhulsesteenweg 6A,
        1560 Hoeilaart
        Belgium.
        Tel:  + 22-658-4243
        Fax:  + 22-658-5118
        Email: Charles.Agboh@ebone.com

        Kundan Singh
        Dept. of Computer Science
        Columbia University
        1214 Amsterdam Avenue, MC 0401
        New York, NY 10027
        USA
        Email: kns10@cs.columbia.edu


        Henning Schulzrinne
        Dept. of Computer Science
        Columbia University
        1214 Amsterdam Avenue, MC 0401
        New York, NY 10027
        USA
        Email: schulzrinne@cs.columbia.edu

        Joon Maeng
        ipDialog, Inc.
        7701 N. Lamar Blvd., Suite 304
        Austin, TX 78752-1023
        USA
        Tel: +1 512-371-1770
        Email: jmaeng@ipdialog.com




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