Route calls from pri trunk to second pri trunk without answering

Hello guru’s,

I am planning a migration, using asterisk 1.4.21 with FreePBX 2.5. The system will have 2 pri trunks, one to pstn and one to an older pbx. I am not configuring extensions on this system at this time and would like to know what the most efficient way to route all incoming calls from the pstn pri to the legacy pbx pri would be. The calls do not need to be answered but I need to preserve incoming callerID and pass it to the legacy pbx. I am thinking a custom destination of,


then an incoming route to match pstn DID that points to the custom destination, but I am not sure if that is the best dialplan commands to use.

Thanks in advance,