Thanks all for the help, I got a step ahead. But in this scenario I am not able to deliver call-id of call-leg a to call-leg b. Extension A is going to make an outbound trunk call: 1. extension calls asterisk (call leg a, call-id 1234567890) 2. asterisk makes outbound trunk call (call leg b, call-id abc123def456) Goal: Put call-id of call leg a in a separate header of call leg b or vice versa (I guess that makes more sense because I have more contorl of the headers inside of my pbx, right?). Following your suggestions I have now call-id b in a separate header of the same call-leg, but in call-leg a. regards, andre