From: Paul Kyzivat <[EMAIL PROTECTED]> > I assume that the obligation of the UAS to put the SDP in the 200 is > removed when it receives a PRACK of a provisional response that had > SDP? That is, if it *doesn't* get PRACKs that it expects, it must put > the SDP in the 200.
I'm not certain it would even get that far. If it has sent a 1xx with 100rel and it doesn't receive a PRACK in response, then I think it will abandon the call at that point. (Though the proper way to abandon the call isn't entirely clear to me.) If it decides to proceed as if the 1xx was unreliable then it would indeed presumably have to follow all the rules that accompany that decision. At the risk of speculating about a feature I've not read the RFC on... It's always possible the 1xx was lost in the network and the UAS must re-send it. The re-send is triggered by the absence of PRACK. I suppose the UAS can abandon sending the 1xx if it desires, too. But if the application layer decides to accept the call, the UAS must send 2xx, and if no 1xx carrying the SDP has been confirmed by PRACK yet, the UAS must be obliged to put the SDP in the 2xx as well. All of that is based on the fact that acceptance of the call can force sending 2xx before the UAS has finished re-sending the 1xx. If the UAS tries to re-send the 1xx several times and gives up, it can probably assume that it has lost connectivity, send 4xx/5xx, and abandon the call. Dale _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
