Airtel launched an innovative VAS - Caller RingBack Tune personalized on the Name of the Subscriber. Suppose if you call on my Airtel Number, you'll hear

Thank You For Reaching Sunil, your call will be answered shortly
MTNL is also offering the same now to its Mobile Customers 2G / 3G for a monthly charge of just Rs 25 / Month.

To activate send an SMS to 56799 with the following format NT YourName Example - NT Sunil