#140 Support for RFC 3326 (respect "Reason" header in CANCEL)

ver devel
core (32)

Section 2 of RFC 3326 says:

Proxies generating a CANCEL request upon reception of a CANCEL from
the previous hop that contains a Reason header field SHOULD copy it
into the new CANCEL request.

In normal SIP operation, a SIP status code in a response provides the
client with information about the request that triggered the
response, the session parameters, or the user. For example, a 405
(Method not allowed) response indicates that the request contained an
unsupported method. A 488 (Not Acceptable Here) indicates that the
session parameters are unacceptable and a 486 (Busy Here) provides
information about the status of the user.

So this means that Proxies SHOULD include the "Reason" header in its CANCEL if it receives a CANCEL containing it.

This would be very useful in big SIP environments involving various proxies.

Another different subject would be Kamailio adding by itself a "Reason" header to inform the cancelled branches about the reason of the cancellation (ie, "Call answered elsewhere"). But this is a different and independent wish/feature.


  • Olle E. Johansson

    Asterisk has support for this header from version 1.6.0.


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