Dear kamailio community, I have a problem that seems really weird. i have the same problem using kamailio 4.3 and 4.4.1. The scenario is the following: I make a call from a sip phone to kamailio. kamailio routes the Invite to an asterisk server. After a while asterisk sends a Bye request to kamailio. Now instead of routing the Bye to the sip phone, I want to create a re-invite request from kamailio and send it to the sip phone. The purpose of the re-invite is to connect the sip phone to another sip phone that already has an active call. This part is working fine but the problem occurs after the sip phone sends the ‘200 OK’ message for the re-invite. Kamailio sends an ACK for the 200 message but this ACK has a ‘CSCall-id’ header instead of the ‘Call-id’ header. To create the re-invite I am using the UAC module with one change to the source code. In the uac.c file found in the tm module folder, I added 2 lines of code to the request function in order to stop the UAC module from creating a from tag(attached). I also attached a trace that shows the ack message with cscall-id. Thank you, Rawad _______________________________________________ SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list sr-users(a)lists.sip-router.org http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users