Hi Udit Of all the methods you have specified, Method 1 and 2 are wrong as per the RFC which states that the sdp of all the provisional and 2xx response of INVITE should be same if they are present.
Both Method 3 and 4 look fine, with method 4 being better because in that case 200 ok for INVITE is only sent when the final negotiation (call media) is done. Hope this helps. -- With Regards Retesh Chadha On 10/2/06, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote: > Hi, > > I want to made an application where we can use early media for playing > initial in-band announcements, and then finally connecting the caller to > actual callee (eg prepaid card application). > > I want to know which is the correct way to support this as per SIP RFC. > > Method 1: > > > Caller Callee > | | > | | > |(1) INVITE with offer | > |---------------------------->| > | | > | | > |(2) 183 with answer 1 | > |<----------------------------| > | | > | | > |(3) 200 OK with SDP | > |<----------------------------| > | | > | | > |(4) ACK | > |---------------------------->| > | | > > > (2) contains SDP of announcement server > (3) contains SDP of callee > > > Method 2: > > Caller Callee > | | > | | > |(1) INVITE with offer | > |---------------------------->| > | | > | | > |(2) 183 with answer 1 | > |<----------------------------| > | | > | | > |(3) PRACK | > |---------------------------->| > | | > | | > |(4) 200 PRACK | > |<----------------------------| > | | > | | > |(5) 200 INVITE with sdp | > |<----------------------------| > | | > | | > |(6) ACK | > |---------------------------->| > | | > | | > | | > | | > > (2) contains SDP of announcement server > (5) contains SDP of callee > > > Method 3: > > Caller Callee > | | > | | > |(1) INVITE with offer | > |---------------------------->| > | | > | | > |(2) 183 with answer 1 | > |<----------------------------| > | | > | | > |(3) PRACK | > |---------------------------->| > | | > | | > |(4) 200 PRACK | > |<----------------------------| > |(5) 200 OK | > |<----------------------------| > | | > |(6) ACK | > |---------------------------->| > | | > |(7)Re-INVITE with SDP | > |<----------------------------| > | | > | | > |(8) 200 OK with SDP | > |---------------------------->| > | | > |(9) ACK | > |---------------------------->| > > (2) contains SDP of announcement server > (5) contains no SDP > (7) contains SDP of callee > (8) contains answer of caller for callee offer > > Her, UDATE can also be used instead of Re-invites. > > Method 4: > > Caller Callee > | | > | | > |(1) INVITE with offer | > |---------------------------->| > | | > | | > |(2) 183 with answer 1 | > |<----------------------------| > | | > | | > |(3) PRACK | > |---------------------------->| > | | > | | > |(4) 200 PRACK | > |<----------------------------| > |(5) UPDATE (callee offer) | > |<----------------------------| > | | > |(6) 200 UPDATE (answer) | > |---------------------------->| > | | > |(7) 200 INVITE | > |---------------------------->| > | | > |(8) ACK | > |---------------------------->| > > > In this case, when callee answers, UPDATE is sent to caller to negoitate > audio with caller, and then 200 OK is sent for the initial INVITE. > > Regards, > Udit > _______________________________________________ > Sip-implementors mailing list > [email protected] > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors > _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
