Transfer with ANI as CID

Our outbound agent is calling customer. At the end of the call the agent needs to transfer to 3rd party company. Currently when it transfer, the 3rd party company will see our company CID instead of the customer.

How to configure FreePBX to have the customer (ANI) as the CID?

Any suggestion is greatly appreciated.

It may be too difficult. To simplify the question, how and where to change outbound callerID. My thought is to change the extensions_override_freepbx.conf, but I am unable to determine the location of the Macro functions (what it does).