Thanks!

I figured it out.  It came to how we were implementing integration with FusionPBX.  We have a process that syncs the FusionPBX domains to the Kamailio domains module.  By default, one of the domains in FusionPBX is the default domain, which has the IP address of the physical server.  So, when calls are routed over to the FusionPBX (using the physical server ip) the loose_route function checks the domain module and thinks the record route (which contains the physical server address) belongs to the Kamailio Server.  Hence, causing the ACK loop.  So, we simply won’t sync the default domain over anymore, which fixes the problem.

On Sep 30, 2022, at 3:55 AM, Denys Pozniak <denys.pozniak@gmail.com> wrote:

Hello!

I also met a similar case and I had to manually handle this behavior.
It is likely that the loose_route() function has determined that you have a strict routing scenario.
But then, in theory, RURI should have its own domain, which is not visible in your trace.


чт, 29 сент. 2022 г. в 14:40, Mack Hendricks <mack@dopensource.com>:
Hey All,

I always struggle with loose_route() and I implemented workarounds in the past.  But, I want to get a better understanding.

I have a  SIP Endpoint -> Kamailio -> FreeSWITCH

The domain and alias is set to the ip address of the Kamailio server (137.184.130.206)

When I get the ACK back from the SIP Endpoint it looks like this

ACK sip:18889072085@137.184.72.42:5060;transport=udp SIP/2.0
Via: SIP/2.0/UDP 10.1.10.140:1052;branch=z9hG4bK-524287-1---740db0025fa217ce;rport
Max-Forwards: 70
Route: <sip:137.184.130.206;lr>
Contact: <sip:1000@50.192.97.226:53790;transport=UDP>
To: <sip:18889072085@dsiptest.dsiprouter.net>;tag=5gv4etZ8tUUcH
From: <sip:1000@dsiptest.dsiprouter.net;transport=UDP>;tag=0af5b751
Call-ID: fWido7VIUKIEI6f6kf4vkQ..
CSeq: 1 ACK
User-Agent: Z 5.5.8 v2.10.17.2
Content-Length: 0

Kamailio will then remove the ACK and change the RURI to itself, which causes an ACK loop.  This is what is look like

ACK sip:137.184.130.206;lr SIP/2.0
Via: SIP/2.0/UDP 137.184.130.206;branch=z9hG4bK3fd.0cf34b683f0627ee2455594ea6cb2517.0
Via: SIP/2.0/UDP 10.1.10.140:1052;received=50.192.97.226;branch=z9hG4bK-524287-1---740db0025fa217ce;rport=1052
Max-Forwards: 69
Contact: <sip:1000@50.192.97.226:1052;transport=UDP>
To: <sip:18889072085@dsiptest.dsiprouter.net>;tag=5gv4etZ8tUUcH
From: <sip:1000@dsiptest.dsiprouter.net;transport=UDP>;tag=0af5b751
Call-ID: fWido7VIUKIEI6f6kf4vkQ..
CSeq: 1 ACK
User-Agent: Z 5.5.8 v2.10.17.2
Content-Length: 0

Question:

What am I missing here?  We have the alias set and we even set it in the domain module (with the register_myself flag).   We have workarounds for this, but I would prefer to figure out how to have Kamailio handle this natively via the loose_route or tm module.

Thanks in advance,

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--

BR,
Denys Pozniak


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