[Kamailio-Devel] How does Kamailio match an ACK for a stateless [3456]XX replied by Kamailio itself?

Alex Balashov abalashov at evaristesys.com
Mon Dec 15 12:31:34 CET 2008

Iñaki Baz Castillo wrote:
> El Lunes, 15 de Diciembre de 2008, Alex Balashov escribió:
>>> I just would like to know how Kamailio handles it, just curiosity. Of
>>> course, the current behaviour seems efficient (Kamailio doesn't need to
>>> generate a server transaction but at the same time it can absorb the
>>> ACK).
>> I could be wrong, but I would have thought that if a reply is being
>> generated by Kamailio itself, statelessly or otherwise, then the ACK
>> would be sent by far the end to the Kamailio host's address in the RURI.
>>    Whereas an end-to-end ACK is addressed and routed to the other
>> endpoint as a sequential request.
> Well, not exactly, ent-to-end ACK only occurs when there is 200 OK for an 
> If an INVITE receives a negative reply from the callee, the the *proxy* 
> generates the ACK and sends it to the callee. After it, the proxy sends the 
> best response (negative in this case) to the caller, and the caller sends ACK 
> for the proxy (it's not an end-to-end ACK).
> Bue anyway, I'm not speaking about it, I'm speaking about the case in which 
> Kamailio replies *stateless* by itself a negative reply.

Oh, I see.  You were asking about only ACKs Kamailio *originates* as 
such, rather than ones it *regenerates*.  Got it.

Alex Balashov
Evariste Systems
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