Different parking ringback

I am using Asterisk 1.4 with polycom 650 for console, incoming calls are answered by receptionist, placed caller into parking at a 700 series number, after it times out, it rings back to the receptionist with the same incoming ringer.

I have tried to add a sipheader to all incoming calls for one unique ring style and then change the ringer on the phone to another style. So I have a unique ring for incoming calls and another unique sound when an another extension call this console but ringbacks from parking have the same incoming sound. Does anyone know how to create a unique ringback?

Thank you