2009/3/2 Attila Sipos <[email protected]>: > When you send the CANCEL, won't the branch be the same as in the INVITE? > > So I can't see what extra advantage is offered by the CSeq. > Can you explain.
CSeq is *not* needed to identify a transaction, just the branch parameter. CSeq is required to identify in-dialog requests in order (also for other stuff related to registration process and so). Also note that when you send a CANCEL the branch parameter will be the same as the INVITE being cancelled, so after it you will receive two replies: a) "200 Cancelled" for CANCEL b) "487 Request terminated" for INVITE Both have the same branch, so *how* to know which reply belongs to CANCEL and which to INVITE? This is only possible by inspecting the method name in the CSeq (in the response to a CANCEL the "CSeq" method has "CANCEL" and "INVITE" in the reponse to the INVITE). Regards. -- Iñaki Baz Castillo <[email protected]> _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
