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

Adnan 112linuxstockholm at gmail.com
Wed Nov 27 20:27:07 CET 2013


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 it
is a known bug or not.

Kamailio receives an INVITE from a gateway and finally responds with 200
OK. Then an ACK is generated by the gateway towards the Kamailio that some
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 case
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()) {
                                } else {

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