Paul Kyzivat wrote: Hello Paul, > > [EMAIL PROTECTED] wrote: > >> Hi Paul, >> >> now I have a problem in my understanding. >> >> A UAC sends out an INVITE with SDP for audio and video to a gateway. >> The gateway >> alters the SIP message to an Non-SIP signal. It sends a 183 with a >> SDP and >> confirms only audio to start early media. But now the caller accepts >> audio and video. > > What do you mean by "the caller accepts audio and video"? It is the > callee that is doing the accepting, and it only accepted audio. So > that is all that will be used as a result of the offer/answer exchange > in this transaction. Sorry, my mistake, of course, I meant the callee. > >> What should the gateway do? If it does not confirm video, video should >> be used. If it confirms video, video will maybe not used. > > I am not familiar with a gateway that can handle video at all. > > If the gateway may want to accept video, then it should decide before > it sends an answer, and the answer should reflect what it has decided > to do. > > OR, if it knows it can accept audio, and wants to accept and enable > early media on the audio while it decides if it will be accepting > video for the call, it can do that a couple of ways: > > 1) It can accept audio only in the invite. After the call is answered, > it can reinvite and add video. > > 2) If the UAC and UAS both support the 100rel option and the UPDATE > method, then the UAS can accept audio only using a reliable > provisional response. If it then later decides, before answering, that > video can be supported, it can send an UPDATE (before the 200 OK) with > a new offer that includes video. > Thank you very much for your really good answers.
Best regards, Markus > Paul > >> Could this scenario happen in pratice? If yes, what is the solution? >> Could the >> gateway have information about the endpoint? >> >> Regards, >> Markus >> _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
