From: =?iso-8859-1?Q?Andreas_Bystr=F6m?= <[EMAIL PROTECTED]> I'm working with a case that involves a call from A that a proxy forks to B and C. I see a potential problem when the following happens: * A sends SDP offer <proxy forks the call to B and C> * B answers with a 183 including a sdp answer * C sends 180 with no spd * C answers the call first, which means C sends a sdp response in the 200 OK.
I have tried to find info on this but have failed to do so. So I was thinking that someone on this forum have already been facing a scenario like this, or maybe know where I can find info on how to solve it in a way that dont violate specs (and also works of course) The source of your problem is that there is a *philosophical* principle that you aren't aware of: When A starts the call, it creates an offer-answer state machine. When A receives the response from B, it changes the state of the state machine. But when A receives the response from C, that response creates a *second* early dialog, which has its own offer-answer state machine, and that state machine is set by the response from C (ignoring what B has sent). How should A handle this (it already got a sdp answer on the offer)? The 183 from B provides an answer within the dialog A-B. The 200 from C provides an answer within the dialog A-C. Of course, this means that A must juggle two early dialogs, and if they are both sending/receiving media, A must decide how to multiplex the media using its user interface. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
