[SR-Users] Wrong handling CANCEL message

[Iñaki Baz Castillo]

2010/4/29 pars3c <pars3c at gmail.com>:
> Hi, i have a problem about the handling of the “cancel” message.

> The B side answer with OK, after a while , a send a CANCEL. I don’t know why
> Kamailio don’t forward this message to the B side.

Because Kamailio already received a 200 for the INVITE transaction so
it's terminated, there is nothing to cancel hen the CANCEL arrives.


> B retry to send the OK message, then A send the ACK.
>
> At the end , B send BYE , but A don’t have the transactin.

This is because Kamailio replied 200 to the CANCEL so A still believes
it has cancelled and has terminated it locally.

Perhaps Kamailio should reply 404 to the CANCEL as a 200 was already
received for the INVITE (could it be a bug?).

 However your UAC is doing strange things:
- Why does A send a CANCEL after receiving a 200 OK for the INVITE?
- Also if A sends an ACK for the 200 (INVITE) it *does* know that the
transaction is still alive so shouldn't reply 481.

The behavior of UAC A is not very common and seems buggy IMHO.

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