[SR-Users] kamailio 4.0.3 - contact header in ACK

Alex Balashov abalashov at evaristesys.com
Wed Nov 27 20:31:06 CET 2013

The only way to diagnose this is to get a full packet capture. In all likelihood, there is a problem with the ACK. 4.0 does not, in principle, mishandle ACKs, no, but loose-routing and NAT problems related to their handling are not uncommon. 

Adnan <112linuxstockholm at gmail.com> wrote:
>We are migrating from our openser 1.4 to kamailio 4.0.3 and have run
>into a
>couple of issues. One of them is described below and we need to know if
>is a known bug or not.
>Kamailio receives an INVITE from a gateway and finally responds with
>OK. Then an ACK is generated by the gateway towards the Kamailio that
>how does not get relayed to the next hop.
>The only special aspect here is that the ACK does not contain a Contact
>header. Is that something that could confuse kamailio and make it
>unable to
>According to SIP RFC, a contact header in ACK is not a must have. Our
>is the one where ACK  is sent by the UAC after receiving a 200 OK final
>response. Everything else about the ACK looks OK e.g. ACK has a branch
>different from the the branch value in the UAC INVITE.
>Is it a a known bug in 4.0.3?
>In the configuration, we handle ACK as below:
>if (is_method("ACK")) {
>                                if (t_check_trans()) {
>                                        t_relay();
>                                        exit;
>                                } else {
>                                        exit;
>                                }
>SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
>sr-users at lists.sip-router.org

Sent from my mobile, and thus lacking in the refinement one might expect from a fully fledged keyboard. 

Alex Balashov - Principal 
Evariste Systems LLC
235 E Ponce de Leon Ave
Suite 106
Decatur, GA 30030
United States
Tel: +1-678-954-0671
Web: http://www.evaristesys.com/, http://www.alexbalashov.com
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