> Hi, > If user A sends INVITE msg to proxy P and it forks this msg to user B1 and > B2. > After B1 and B2 reply with provisional response with different To tag. > If user A decides to cancel this call, it sends CANCEL msg without To tag to > proxy P > > 1. Does proxy P need to add different To tag in the CANCEL msgs it sends to > B1 and B2? No. The CANCEL should look exactly like the INVITE. Hence the CANCEL to B1 and B2 must not contain a To tag. > 2. Proxy P needs forward both 487 msgs from B1 and B2 to user A with > different To tag, is it true? No again. If both branches return 487, P should ACK each branch and forward only a single 487 upstream. The 487 forwarded upstream by P could have one of the two To tags received. Refer Section 16.7 Point 6 of bis-09 for more details on forwarding of the best response and choosing the (arbitrary) To tag. > 3. Do b1 and b2 need to add To tag in the 200 response(for CANCEL) ? Yes, which is equal to the To tag in the 487 response to the original request. Refer Section 9.2 of bis-09. > 4. When should the proxy P send 200(for CANCEL) to user A? > After it receives both 200 msgs from b1 and b2, is it true? P can send a 200 to CANCEL immediately. It need not wait for the individual branches to respond with a 200. Subhash Nayak Hughes Software Systems http://www.hssworld.com _______________________________________________ Sip-implementors mailing list [EMAIL PROTECTED] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
