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

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,