Issabel pbx Call back routing

previously this solution is at Elastix PBX, now we want to move it to issabel pbx. telemarketing environment using a prefix XX to call out and will pickup random DID from database tables. there have a php trigger during outbound call and track this last called ID (customer) is below to which agent. if customer call back will return back to correct agent. I have the PHP script and database structure but I don't know how to implement at issabel pbx.