Hi Gary, (since no-one else has replied...)
I don't know but isn't the origin the "controller" of the SDP? So, if you've got some kind of 3rd party thing which is controlling the content of the SDP, then that'd be shown in the o= line. Whereas the c= line (obviously) just tells you where to send the media. I would agree that it doesn't seem to have any specified active role (so far) but seems to be there for informational purposes only. I also agree that it doesn't seem to have any role in offer/answer. So, that's my opinion. Regards, Attila -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Gary Cote Sent: 13 December 2006 17:18 To: sip-implementors Subject: [Sip-implementors] Significance of address in the SDP origin line Short version: does the address field in the origin line have any particular significance in SIP? I'm thinking no, but would appreciate a second opinion. Long version: Here's an snippet from a 183 response with SDP answer that I captured: Contact: <sip:[EMAIL PROTECTED]:10000> o=Sonus_UAC 7952 20059 IN IP4 69.59.245.131 c=IN IP4 69.59.245.132 I was explaining to someone what the various addresses in a SIP message mean. For example, one could say that the address in the Contact header specifies where the UA wants to receive SIP messages; and the address in the c= line is where it wants to receive RTP/RTCP packets. Note that the origin address is different from either of these. I couldn't think of any particular use for that address field. And after searching the various specs and mailing lists, I still can't come up with one. So ... I've tentatively concluded that the address has no particular relevance to SIP call setup or the offer/answer exchange (other than the fact that all of the fields in the origin line are used to identify a unique SDP). Would anyone care to comment on that? -- Gary Cote www.awardsolutions.com _______________________________________________ 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
