[Spce-user] Weird situation with End2End ACKs from a carrier

[Raúl Alexis Betancor Santana]

Hello everyone, 

I'm trying to figure out what's happening (at random) with calls that we receive from one carrier. These weird calls get dropped or never stablished, because when we receive the ACK to the 200 Ok SPCE send back to the carrier proxy, that that ACK transverse the kamailio-proxy instance of SPCE, it get it From: field masked wrongly, so the B2BUA (sems) refuses it and drops the A leg of the call. 


One example: 

Overall view of the weird call 


The first ACK (ACK forwarded from kamailio-lb sip-int to kamailio-proxy) looks like: 


The sencond ACK (ACK forwarded from kamailio-proxy to sems) looks like: 

As you could see, the From on the second ACK get weird, also non RFC compliant and then sems refuse it and at the end, the call gets dropped. 

I've been trying to figure out what part of the proxy routing script it's responsible of this, but didn't find any uac_replace call or anything related 


This only happens on a 10:2 basis on the incoming calls ... but get people annoyed ... because the hear the the other end and begins their conversation and suddendly the call gets dropped. 

Any clue about what could be happening? ... it only happers with this USA based carrier, everything else works perfect. 

Its a SPCE mr7.5.3 with the latest patches ... but this happens since we upgraded from 5.5.1 to 7.5.3 

Best regards. 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sipwise.com/pipermail/spce-user_lists.sipwise.com/attachments/20200309/1d76059b/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 588128.1349999991
Type: image/png
Size: 74644 bytes
Desc: not available
URL: <http://lists.sipwise.com/pipermail/spce-user_lists.sipwise.com/attachments/20200309/1d76059b/attachment-0001.1349999991>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 674422.1999999937
Type: image/png
Size: 50085 bytes
Desc: not available
URL: <http://lists.sipwise.com/pipermail/spce-user_lists.sipwise.com/attachments/20200309/1d76059b/attachment-0001.1999999937>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 799965.5949999942
Type: image/png
Size: 46828 bytes
Desc: not available
URL: <http://lists.sipwise.com/pipermail/spce-user_lists.sipwise.com/attachments/20200309/1d76059b/attachment-0001.5949999942>