> When the CANCEL request contains a CSeq number > that is not the same as the INVITE request it > is trying to cancel, what is the appropriate > error message to be sent to the UAC?
Per rfc3261 section 9.2, a 481 response SHOULD be sent. However since the 481 will likely be interpreted like real transaction already forgotten or the dialog usage is gone, the 481 might not actually be the desired choice. If the Via branch indicated that the CANCEL matched and there was only cseq issues, a 400 response could be sent. Since CANCEL 200 does not really indicate that anything was successfully cancelled, a 200 response may be sent. However you'd likely want to highlight the abnormal situation within status-line's reason-phrase. _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
