Many thanks for your help. I've applied the patch, recompiled and I see no difference unfortunately. The ACK is not forwarded, and execution after t_relay stops.  I've set the debug level to 4 and captured the traces - I believe the section dealing with the ACK is there:  https://pastebin.com/TG03YQWC KR J. On Fri, Dec 22, 2017 at 11:59 AM, Daniel-Constantin Mierla < miconda(a)gmail.com > wrote: >Hello, >can you give a try with latest master branch or by > using the patch from next link? >  - https://github.com/kamailio/kamailio/commit/52111974b4571e0562e8e731df80f48… >Apparently the t_realy() stopped script execution (by > returning 0) when e2e ACK forwarding was successful. The > patch should change that to return true. >If all works fine while testing, then I will backport. >Cheers, >Daniel > > >On > 22.12.17 14:05, Jean Cérien wrote: >> >>Hello >>I've tried mhomed = 1 with no luck - not so >> sure what you mean by default route, I've added >> listen = udp:myadsress:5060 >>I also have auto_aliases=no and >> alias=myaddress >> >>However, what bugs me is that execution >> seems to stop INSIDE t_relay and the info >> message after the t_relay is not displayed.  >> >>I hate to say this, but could this be a bug >> ? >> >>Rgds >>J. >> >> >>On Fri, Dec 22, 2017 at >> 1:52 AM, Sergey Safarov < s.safarov(a)gmail.com > wrote: >>>Check that your installation >>> have one NIC with only one default route on >>> host. >>>If not check that "mhomed=1" is >>> enabled. >>> >>>Sergey >>>пт, 22 дек. 2017 г. в 0:02, >>> Jean Cérien < cerien.jean(a)gmail.com >: >>>> >>>>Hello >>>>I am using kamailio 5.0.2, on a >>>> debian 9 system. >>>> >>>>Everything was running fine, until >>>> one of our voip provider changed his >>>> switch. Our kamailio is relaying >>>> between several voip providers and >>>> several asterisk (only the >>>> signalisation, no rtp). >>>> >>>>When we get an invite from this new >>>> switch, we select an asterisk and >>>> relay it correctly to this box. >>>> However, the OK is relayed back. But >>>> when the voip providers sends an ACK >>>> for this OK, the t_relay function does >>>> not return at all, it just dies with >>>> no action and no error. >>>> >>>>Here is the snippet from >>>> route(relay) >>>> >>>>        >>>> xlog("L_INFO","route(relay)  @@ $rm >>>> - Source: $si:$sp, fu:$fu, tu:$tu\n" >>>> ); >>>>        >>>> $var(restrelay)=t_relay(); >>>>        >>>> xlog("L_INFO","route(relay)  @@ $rm >>>> - t_relay result: $var(restrelay)" >>>> ); >>>>        if (!$var(restrelay)) { >>>> >>>>When processing the initial invite, >>>> I do get both INFO messages. When the >>>> ACK is processed, I only get one INFO >>>> message, and no ACK is relayed - so it >>>> seems execution dies in the t_relay >>>> >>>>What could be wrong ??? >>>> >>>>J. >>>> >>>>Details of the ACK: >>>> >>>>ACK sip:dialednumber@kamailioIP :5060 >>>> SIP/2.0 >>>>Via: >>>> SIP/2.0/UDP >>>> VOIPPROVIDERIP:5060;branch=z9hG4bKjq16fi00d85uee181ic0.1 >>>>To: <sip:kamailioIP:5060> ;tag=as7f10ed48 >>>>From: >>>> < sip:sourcenumber@orange-multimedia.fr >;tag=SD8u3ob01-7dd8efde-0002-00d5-0000-0000 >>>>Call-ID: >>>> SD8u3ob01-688d41f5e2164ceeafe76f40b82b3f97-v300g00030 >>>>CSeq: >>>> 1 ACK >>>>Max-Forwards: >>>> 66 >>>>Content-Length: >>>> 0 >>>>Route: >>>> < sip:kamailioIP;lr=on;ftag= SD8u3ob01-7dd8efde-0002-00d5-0000-0000;did=a0b.49d> >>>> >>>> >>>> >>>>(should you have enough width; the >>>> diagram will look ok) >>>> >>>>  >>>>                  VOIP PROVIDER    >>>>            KAMAILIO                >>>>        ASTERISK >>>>  >>>> 21:38:54.685149   │ >>>> ──────────────────────────> │  >>>>                            │    >>>>▒  >>>>       +0.000451    │  100 trying -- >>>> your call is │                    >>>>          │    >>>>▒ >>>> 21:38:54.685600   │ >>>> <────────────────────────── │  >>>>                            │    >>>>▒  >>>>       +0.000084    │                >>>>              │        INVITE >>>> (SDP)         │    >>>>▒ >>>> 21:38:54.685684   │                >>>>              │ >>>> ──────────────────────────> │  >>>>   >>>>▒  >>>>       +0.000831    │                >>>>              │         100 Trying  >>>>         │    >>>>▒ >>>> 21:38:54.686515   │                >>>>              │ >>>> <────────────────────────── │  >>>>   >>>>▒  >>>>       +0.000471    │                >>>>              │        200 OK >>>> (SDP)         │    >>>>▒ >>>> 21:38:54.686986   │                >>>>              │ >>>> <────────────────────────── │  >>>>   >>>>▒  >>>>       +0.000394    │        200 OK >>>> (SDP)         │                    >>>>          │    >>>>▒ >>>> 21:38:54.687380   │ >>>> <────────────────────────── │  >>>>                            │    >>>>▒  >>>>       +0.038694    │            >>>>  ACK             │                >>>>              │    >>>>▒ >>>> 21:38:54.726074   │ >>>> ──────────────────────────> │  >>>>                            │    >>>>▒  >>>>       +0.060155    │                >>>>              │        200 OK >>>> (SDP)         │    >>>>▒ >>>> 21:38:54.786229   │                >>>>              │ >>>> <<<──────────────────────── >>>> │    >>>>▒  >>>>       +0.000138    │        200 OK >>>> (SDP)         │                    >>>>          │    >>>>▒ >>>> 21:38:54.786367   │ >>>> <<<──────────────────────── >>>> │                             │    >>>>▒  >>>>       +0.005721    │            >>>>  ACK             │                >>>>              │  >>>> >>>> >>>>_______________________________________________ >>>>Kamailio (SER) - Users Mailing List &gt;&gt;&gt;&gt;sr-users(a)lists.kamailio.org >>>>https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users >>> >>>_______________________________________________ >>>Kamailio (SER) - Users Mailing List &gt;&gt;&gt;sr-users(a)lists.kamailio.org >>>https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users >>> >> >> >> >>_______________________________________________ >>Kamailio (SER) - Users Mailing List &gt;&gt;sr-users(a)lists.kamailio.org >>https://lists.kamailio.org/cgi-bin/mailman/listinfo/sr-users >> >-- >Daniel-Constantin Mierla >www.twitter.com/miconda -- www.linkedin.com/in/miconda >Kamailio Advanced Training - www.asipto.com >Kamailio World Conference - May 14-16, 2018 - www.kamailioworld.com