Caller ID from a forwarded number at different "Rate Center"

We recently relocated our office to a different “Rate Center”. In order to keep our existing numbers, AT&T suggested that we port the numbers to Wireless Call Forwarding (WCF) service which would forward our existing numbers to a new set of numbers for the analog lines.

When we make calls out, our Caller ID shows up with the new set of numbers. How can we get AT&T to display our old numbers as the Caller ID? They said it is not possible. Any ways around it? I have set the Caller ID on FreePBX’s Trunk page but it is not working.

Thank you!