RFC 3428, "Session Initiation Protocol (SIP) Extension for Instant Messaging", December 2002

Note: This RFC has been updated by RFC 8591

Errata ID: 2261
Status: Held for Document Update
Type: Technical
Publication Format(s) : TEXT
Reported By: Brett Tate
Date Reported: 2010-05-13
Held for Document Update by: Robert Sparks

Section 10 says:

MESSAGE sip:user2@domain.com SIP/2.0
Via: SIP/2.0/TCP proxy.domain.com;branch=z9hG4bK123dsghds
Via: SIP/2.0/TCP user1pc.domain.com;branch=z9hG4bK776sgdkse;
                                           received=1.2.3.4
Max-Forwards: 69
From: sip:user1@domain.com;tag=49394
To: sip:user2@domain.com
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Type: text/plain
Content-Length: 18

Watson, come here.

The message is received by user2, displayed, and a response is
generated, message F3, and sent to the proxy:

SIP/2.0 200 OK
Via: SIP/2.0/TCP proxy.domain.com;branch=z9hG4bK123dsghds;
                                         received=192.0.2.1
Via: SIP/2.0/TCP user1pc.domain.com;;branch=z9hG4bK776sgdkse;
                                            received=1.2.3.4
From: sip:user1@domain.com;tag=49394
To: sip:user2@domain.com;tag=ab8asdasd9
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Length: 0

Note that most of the header fields are simply reflected in the
response.  The proxy receives this response, strips off the top Via,
and forwards to the address in the next Via, user1pc.domain.com, the
result being message F4:

SIP/2.0 200 OK
Via: SIP/2.0/TCP user1pc.domain.com;branch=z9hG4bK776sgdkse;
                                           received=1.2.3.4
From: sip:user1@domain.com;;tag=49394
To: sip:user2@domain.com;tag=ab8asdasd9
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Length: 0

It should say:

MESSAGE sip:user2@user2pc.domain.com SIP/2.0
Via: SIP/2.0/TCP proxy.domain.com;branch=z9hG4bK123dsghds
Via: SIP/2.0/TCP user1pc.domain.com;branch=z9hG4bK776sgdkse;
                                           received=1.2.3.4
Max-Forwards: 69
From: sip:user1@domain.com;tag=49583
To: sip:user2@domain.com
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Type: text/plain
Content-Length: 18

Watson, come here.

The message is received by user2, displayed, and a response is
generated, message F3, and sent to the proxy:

SIP/2.0 200 OK
Via: SIP/2.0/TCP proxy.domain.com;branch=z9hG4bK123dsghds;
                                         received=192.0.2.1
Via: SIP/2.0/TCP user1pc.domain.com;branch=z9hG4bK776sgdkse;
                                           received=1.2.3.4
From: sip:user1@domain.com;tag=49583
To: sip:user2@domain.com;tag=ab8asdasd9
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Length: 0

Note that most of the header fields are simply reflected in the
response.  The proxy receives this response, strips off the top Via,
and forwards to the address in the next Via, user1pc.domain.com, the
result being message F4:

SIP/2.0 200 OK
Via: SIP/2.0/TCP user1pc.domain.com;branch=z9hG4bK776sgdkse;
                                           received=1.2.3.4
From: sip:user1@domain.com;tag=49583
To: sip:user2@domain.com;tag=ab8asdasd9
Call-ID: asd88asd77a@1.2.3.4
CSeq: 1 MESSAGE
Content-Length: 0

Notes:

The corrected text changes F2's request-uri to reflect the binding.
The corrected text proxies received From tag instead of changing it.
The corrected text removes various extra semicolons show within example.

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