I think we need to seriously take a look at this. IMHO, the source needs to set up a dialog a long time before the actual paging can start. Otherwise, there will be a burst of INVITE which will make this difficult in offices with lets say 1000 phones. Then the phone must listen to the multicast group all the time and play the annoucement whenever there is a paging going on.
I think the SDP would look like this: v=0 o=carol 28908764872 28908764872 IN IP4 224.3.4.5 s=- c=IN IP4 224.3.4.5 t=0 0 a=multicast-recvonly m=audio 3000 RTP/AVP 0 a=rtpmap:0 PCMU/8000 m=audio 3002 RTP/AVP 3 a=rtpmap:3 GSM/8000 I think we need an attribute like the "multicast" (just a wild guess) that indicates that the UA should just listen to that group and not send any media to the group. In the example above, the phone could tune into PCMU or GSM codecs on different ports. Any other ideas? Christian > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf > Of CTO YAN Renxiang > Sent: Tuesday, June 06, 2006 4:01 AM > To: [email protected] > Subject: [Sip-implementors] How to create a multicast session > using SIP? > > Hi, all, > > How to create a multicast session using SIP? Is the following > description correct? Two kinds of case: > Case (1) A invites B to join a multicast session. > -A sends a INVITE to B, the multicast address is included in > SDP part of INVITE message. > -B will then join the session by sending an IGMP to join the > multicast session. > -but when will A join the session? > > Case (2) A joins a multicast session independently. > A sends INVITE to whom? when send IGMP join message? > > Other cases? > > Regards, > Renxiang <mailto:[email protected]> > _______________________________________________ > 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
