Udit, IMO usage of non-reliable 183 for play-collect scenarios is not the best way. A non-reliable response is not guaranteed end-to-end. Probably the reason why you need the same SDP in non-reliable 183 and the following 200. In case you need to avoid completing the connection of A unless C is connected (to not charge on play-collect?), the mechanism to use is RPR (PRACK), possibly used in conjuction with UPDATE. rgds, -vishal
________________________________ From: [EMAIL PROTECTED] on behalf of [EMAIL PROTECTED] Sent: Tue 8/16/2005 8:46 AM To: Paul Kyzivat Cc: SIP Implementors Subject: Re: [Sip-implementors] SDP in 183 Session Progress Hi Paul, In what case does UAS first sends 183 response with SDP followed by 200 ok with same SDP, if it is for early announcement, then why it will send 200 OK with same SDP. Consider following scenario: 1) User A calls 1800.. number 2) Call Controler connects it to announcement server which sends 183 SessionProgress response 3) User A hears announcement and dials the digits for party C. 4) Call Controller initiates new connection to new party C by sending INVITE (no SDP) 5) C answers the call using 2xx response (with its SDP) 6) Call Controller sends 2xx response to user A with SDP of C Is it necessary to use PRACK mechanism for this scenario ? -Udit Paul Kyzivat <[EMAIL PROTECTED]> Sent by: [EMAIL PROTECTED] 08/15/2005 07:40 PM To Udit Goyal/C/US/[EMAIL PROTECTED] cc SIP Implementors <[email protected]> Subject Re: [Sip-implementors] SDP in 183 Session Progress [EMAIL PROTECTED] wrote: > Hi, > > Is it specified anywhere in RFC 3261 that if SDP received in 183 Session > Progress response, > UAC should establish RTP connection. (not talking about PRACK mechanism) The UAS (the one sending the answer) must be prepared to receive as soon as the answer is sent. But I don't believe anything compells the UAC to send to it. (Ever, even after the 200.) However there is probably some requirement to send RTCP eventually, so maybe if it takes a really long time before the 200 you might have to send it. > And if UAS sends 200 OK after 183 in this case, can he send different SDP > compared to what was present in 183 response. They are required to be the same when PRACK is not in use. Paul > Regards, > Udit > _______________________________________________ > Sip-implementors mailing list > [email protected] > http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
