In SIP, multimedia negotiation is done within the three required messages for session initiation:
INVITE + SDP 200 OK + SDP ACK + SDP FOllowing those three messages, both parties have agreed to talk to eachother and agreed on the media CODECs and IP/Ports to use for the streams. There is no need to use up another port for call parameter negotiation. To change media settings mid-call, SIP uses REINVITE. Everything with SIP is Fast Start as shown above with the 3-message call setup. BR, Aaron -----Original Message----- From: [EMAIL PROTECTED] on behalf of mohammad Sent: Tue 12/28/2004 4:35 PM To: [email protected] Subject: [Sip-implementors] sip call control Hi; As you probably know, in H323 protocol stack, there is call control protocol which is named H245. In normal call flow , after the call is established a seperate tcp channel will open for H245 messages. As I understand from RFC 3261 and some documents, SDP will handle the call control in SIP. Now my questions are: 1) when SDP messages is going to handle? (after call establishment or during call setup) 2) like H323 , can we have both normal-start and fast-start call flow in SIP? 3)Is there any document, indicating the diffrences between SIp and H323? Warmest Regards Mohammad _______________________________________________ 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
