> Since usage of 481 as per RFC 3261 seems to have > its cons, is it correct to interpret that > the CANCEL with incorrect CSeq number is a > request that attempts to cancel > a non-INVITE transaction?
There is no reason to interpret it that way. > In case such an interpretation is correct, can a > 405 response be sent for the CANCEL? There is no reason to send CANCEL 405 response unless you don't support CANCEL. Based upon lack of Allow for CANCEL 405 within RFC 3261 section 2, I assume that most devices would be surprised to receive such a response. The CANCEL 481 can have interop issues; however rfc3261 does say that it SHOULD be sent. RFC 5057 section 5.1 also discusses it: "The 481 response to a CANCEL request has to be treated differently. For CANCEL, a 481 means the UAS can't find a matching transaction. A 481 response to a CANCEL affects only the CANCEL transaction. The usage associated with the INVITE is not affected." _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
