[SR-Users] Wrong handling CANCEL message

[Iñaki Baz Castillo]

2010/5/4 Alex Hermann <alex at speakup.nl>:
> On Friday 30 April 2010 13:25:13 Iñaki Baz Castillo wrote:
>> Yes, I agree. In fact draft invfix solves it by adding a new state
>> "Accepted" so when a 200 is sent the server transaction remains in
>> memory for a while (to absorbe INVITE retransmissions).
>>
>> But anyway the transaction is in "Accepted" state, and not in
>> "Proceeding", so a CANCEL should have no effect and the proxy
>> shouldn't reply 200 for the CANCEL as the proxy has canceled
>> *nothing*.
>
> The response to the CANCEL doesn't indicate if anything has been canceled
> (just that the CANCEL is well received), the response to the INVITE does.
> Answering 200 OK to the CANCEL is the least interuptive response as it won't
> trigger an error in the UAC. A 481 might trigger that the call is aborted as
> the UAC might think the dialog is invalid. If the 200 OK is received by the
> UAC, it should handle it just like the well known INVITE + 200 OK / CANCEL
> race for which it should send a BYE if the dialog is to be ended.

Interesting point of view. Maybe it's just easier as you describe.


-- 
Iñaki Baz Castillo
<ibc at aliax.net>