> Hi, I have another question regarding Session Timer: > > If the refresher is uac, how can the uas > determine the re-INVITE is for the purpose of > session refresh? (assuming uas needs to tell > the difference between a Session Refresh > re-INVITE and other purpose re-INVITEs so > that it can pursue different process. ) > > There could be re-INVITEs that are Target > Refresh Request (RFC3261 12.2), and > re-INVITEs that change SDP. > > My idea is to determine by checking if the > header part contains "Supported: timer", but > I am not sure this condition is good enough.
SIP currently does not provide a very complete mechanism to communicate what is trying to updated by a re-INVITE/UPDATE or what was successfully updated. The receiver basically has to analyze the request for every header/body that it willing to allow to be updated; and basically nothing should be updated if a failure response is returned. The following thread provides a little detail concerning the issue. http://www1.ietf.org/mail-archive/web/sip/current/msg08077.html Concerning your specific question, the RFC indicates that the origin line of the SDP is used to indicate when the SDP changes. However a request to update headers (Contact, Session-Expires, etcetera) and the SDP can occur at the same time. _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
