Hello, I was wondering about the below scenario and if it's possible to do in FreeSwitch: The setup is like this: Carrier --- FreeSwitch --- Kamailio --- UAS The UAS sends a SIP INVITE to Kamailio. Kamailio relays the INVITE to FreeSwitch. FreeSwitch creates a new call leg towards the Carrier (new INVITE). So far pretty basic. When the carrier responds back with a 200 OK, I need to append the Call-ID of the 200 OK to the 200 OK of the initial INVITE as a custom header. Is this possible? Regards, Grant