Hi! On Thu, Jun 12, 2008 at 4:56 PM, Benny Prijono <bennylp at pjsip.org> wrote: > On Thu, Jun 12, 2008 at 2:22 PM, Sasa Coh <sasacoh at gmail.com> wrote: > > Hi, > > > > Thanks Benny, I got it. Well, we have no To-tag change and unreliable > > transport. > > Is there any other SIP scenario/call flow (supported by pjsip) that would > > handle such functionality? > > Scenario again: The client receives (after 18x) tones or announcements > from > > media server and when other party answers (2xx) the SDP is changed. > > > > Since the To-tag doesn't change, probably we can try this. Basically > we will force the server to not change the SDP between 18x and 2xx > response, by using reliable response. Hopefully this will make the > server sends the new SDP with UPDATE or re-INVITE, which we support. > > You can force the server to send answer reliably either with using TCP > or TLS transport, or using reliable provisional response extension > with --use-100rel option (in pjsua). > > If the server still sends modified SDP in 2xx, at least we can then > blame it for being non-compliant. ;-) Thanks a lot Benny. That's exactly what I need :-) bye, sasa > > Cheers > Benny > > > > thanks again, > > sasa > > > > On Thu, Jun 12, 2008 at 2:52 PM, Benny Prijono <bennylp at pjsip.org> > wrote: > >> > >> On Thu, Jun 12, 2008 at 11:59 AM, Sasa Coh <sasacoh at gmail.com> wrote: > >> > Hello Benny! > >> > > >> > I have question regarding SDP negotiation process. We managed to > >> > establish > >> > signaling connection with the other party but there was no (correct) > >> > voice > >> > path established. > >> > > >> > Here is how it goes: > >> > - pjsua makes call through Call Agent: INVITE with SDP (offer). > >> > - Call Agent responds with 180 Ringing with SDP (answer). Here SDP > >> > points > >> > to the Media Server that provides "Ring Back" tone to the caller. > >> > - When called party accepts the call, Call Agent sends 200 OK with > yet > >> > another SDP (offer/answer?) points to the called party. > >> > - After that there is no voice path? to be exact, voice path is still > >> > established to the media server providing tones but not to the called > >> > party > >> > as directed in the latter SDP. > >> > > >> > The same situation works with other clients (X-Lite). > >> > > >> > Does pjsip support this kind of SDP negotiation? Should we handle some > >> > callback we are not aware of? > >> > > >> > >> I think this is quite a complicated scenario, and which one it is > >> depends on whether the server changes the To tag between 18x and 2xx > >> response. If it does change, then this is a similar scenario to > >> forking with early media, which we don't handle at PJSUA-LIB level (we > >> do have basic forking handler at PJSIP level, but I don't implement > >> forking at PJSUA-LIB level due to complexities in handling the media). > >> > >> If the To-tag doesn't change, then it further depends on whether the > >> SIP transport is reliable or not. If the transport is not reliable, it > >> means server is sending "provisional" SDP in 18x response and the > >> "final" SDP in the 2xx response which the UAC should use. This, albeit > >> hairy is a valid SIP scenario. But we don't seem to handle this > >> either. If the transport is reliable, then the SDP in 18x is the final > >> one and UAC must ignore the SDP in 2xx since it belongs to the same > >> transaction, and if this is the case, PJSIP is doing the right thing. > >> > >> So there you go. :) > >> > >> Cheers > >> Benny > >> > >> _______________________________________________ > >> Visit our blog: http://blog.pjsip.org > >> > >> pjsip mailing list > >> pjsip at lists.pjsip.org > >> http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org > > > > > > _______________________________________________ > > Visit our blog: http://blog.pjsip.org > > > > pjsip mailing list > > pjsip at lists.pjsip.org > > http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org > > > > > > _______________________________________________ > Visit our blog: http://blog.pjsip.org > > pjsip mailing list > pjsip at lists.pjsip.org > http://lists.pjsip.org/mailman/listinfo/pjsip_lists.pjsip.org > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20080613/d5a4b8d4/attachment.html
