Hi Manish! Say UAC has sent an INVITE and now suddenly he wants to cancel that INVITE by sending CANCEL request(assuming 1xx response to INVITE has comeback to UAC). In this case for the UAC dialog is still not created. As per rfc 3261 CANCEL is a different transection but it works in the context of the earlier request which it(CANCEL) has to cancel(in this case INVITE) before INVITE-200 OK dialog matures. Now in this sscenario branch parameter in initial INVITE is crucial as it is the only transection identifier for CANCEL .
Also the intermediate proxy that occured in the path of INVITE earlier will match the CANCEL with the transection for which it has come. Regards Achint Manish Jain <[EMAIL PROTECTED]> Sent by: [EMAIL PROTECTED] 10/08/2006 08:53 PM To [email protected] cc Subject [Sip-implementors] Use of Branch Parameter Hello Friends, I believe that branch parameter is used to identify transaction until dialog is created. Once dialog is created callid, from-tag and to-tag is used to identify the dialog. branch param is mainly used by proxies to identify transactions in case of parallel forking. I can't understand why a UAC(phone) will need to send branch parameter in first originating request. Please throw some light. Best Regards, Manish Jain __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors *********************** FSS- Confidential *********************** _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
