iPhone 4 & Audi MMI Ringtone

I have recently bought an Audi A1 which comes with the bluetooth connection for the phone.

However, when I receive an incoming call I get my iPhone ringtone coming through the speakers instead of the Audi ringtone. Is there anyway to change which ringtone to hear (iPhone or Audi) or does the iPhone software only allow it's ringtone to be heard?