Hi, I think both Method 1 and Method 2 are possible. 1. if the Invite coming from caller without support:100rel. Method could be the flow. 2. if the Invite coming from caller with support:100rel. It means the end to end reliablity has to be guranteed, so the PRACK and 200 OK is necessary. If no PRACK, the 183 should be re-sent.
Best regards, Yulung >From: "Christer Holmberg (JO/LMF)" <[EMAIL PROTECTED]> >To: <[EMAIL PROTECTED]>, <[email protected]> >CC: [email protected] >Subject: Re: [Sip-implementors] [Sip] Early media query >Date: Mon, 2 Oct 2006 14:57:29 +0200 > > >Hi, > >You can use Method 2, assuming the 18x and 200 have different To tag >values. Otherwise you can use Method 3 or 4 (message 9 in Method 3, and >message 7 in Method 4, seem to go in the wrong direction, though). > >Regards, > >Christer > > > > > > > >________________________________ > > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] > Sent: 2. lokakuuta 2006 12:57 > To: [email protected] > Cc: [email protected] > Subject: [Sip] Early media query > > > > 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 _________________________________________________________________ Don't just search. Find. Check out the new MSN Search! http://search.msn.com/ _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
