[SR-Users] Differentiation between ACK INVITE and ACK CANCEL

[Alex Balashov]

Hi Adrien,

On 07/06/2010 10:39 AM, inge wrote:

> Firstly, I was thinking to make a difference using the CSeq field, but
> it seems that the CSeq on ACK contains the ACK himself. Probably because
> ACK is a request and not a response.

You are correct;  ACK is a wholly different request and a separate 
transaction from the exchange it is meant to acknowledge.

It is possible to differentiate end-to-end vs. hop-by-hop ACKs using 
t_check_trans():

http://www.kamailio.org/docs/modules/3.0.x/modules/tm.html#t_check_trans

See its usage in the stock kamailio.cfg.

Note that 200 response to CANCEL does not generate an ACK, but a 487 
response does, so your question is rather academic.

-- 
Alex Balashov - Principal
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