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Re: [Sip] SIP backward compatibility issue




Rohan Mahy wrote:
On Tuesday, December 24, 2002, at 09:45 AM, Steve Levy wrote:

At 11:46 AM 12/24/2002 -0500, Jonathan Rosenberg wrote:

Early media was not specified in rfc2543. It did say that you should be prepared to receive media before receiving the answer, which is still the case for 3264. Another issue was that people used to put SDP in non-reliable 1xx responses, and then put the same thing in 2xx. That case is explicitly allowed for in 3261, so it should interoperate as well.

Perhaps you could identify the specific problem you are concerned about?

my concern was SDP in a 18x followed by another 18x/2xx with different SDP. Wouldnt the SDP in the subsequent 18x/2xx be treated differently by 3264 compliant UAs as opposed to earlier 2543 compliant UAs ?

Because offers and answers need to be sent reliably, you can't put an answer in a non-reliable 18x and an offer in a 2xx. This is spelled out in 3261 section 13 as quoted below...
All of this supposed "rfc2543 behavior" was never documented in rfc2543, and is rather one of several interpretations people have made about the spec. Even supposedly "rfc2543-compliant" UAs probably wont interwork for features like this.

-Jonathan R.

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