5> PROXY construct this message with same Request-URI, TO , FROM, CALL-ID and Cseq number field values of the INVITE message send to caller B and insert it own VIA header field value. the branch id is different from the one which is sent in INVITE message to caller B.
Ah, your problem is the branch ID, you are having a branch ID which is different from that of the INVITE you want to CANCEL. While constructing the CANCEL, ensure that you have the same branch ID as that of the INVITE you want to cancel. Branch ID is the main key for transaction matching. Once UAC (caller B in your case) gets the CANCEL, it cannot find any matching transaction and hence UAC sends 481 back. If you send the same branch ID as that of the INVITE you want to cancel, transaction matching should be successful and you should get 200 OK for the CANCEL message. Refer RFC 3261 : As discussed below, a CANCEL request will have the same value of the branch parameter as the request it cancels. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Thanks & Regards Monica Ingudam (Mail: [EMAIL PROTECTED]) Signal Engineer AOL Dulles _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
