The proliferation of Mobile Telephony and Mobile Data Services along with the tight integration of voice, text messaging, email and other data services have ignited an explosion of Value Added Services targeted directly at the mobile user.Color Ring Back Tone (CRBT) is one of the many Value Added Services that has seen incredible adoption in recent years. CRBT allows customization of the ring back tone. When a call is placed, the caller hears an audible alert through the phone. The alert that indicates that a call is successfully going through is called the Ring Back Tone. A CRBT service allows the person who is being called select the Ring Back Tone (or replace with a recorded message or song) based on the Caller ID of the person who is calling them.This paper deals with the implementation of a CRBT service, although it is just one example of the many mobile services that can be delivered using this same architecture.