Trunk forwarding


I’m new to asterisk and the FreePBX-Distro. My search for any inspiration on how to configure a call forwarding from one trunk to another ended barren of results.

I figured out how to configure my trunks (BRI1 and GSM1) and the machine is anwsering on both. Since there is no extention and no route defined the box anwsers the call, tells the caller that there is no route and terminates the call. So far so good.

My Question is: How can I configure a call forwarding from all incomming calls on trunk BRI1 to call a certain number via trunk GSM1?

My system: FreePBX, one BRI card with one port in use and one GSM card with one SIM card inserted.

Thanks in advance