tree 96bf6f30467aa6e2b83c6398ed784526442af9a3
parent 0647b580aa7874311fc77b659e4f646750ddd74e
author John Wang <johnwang@google.com> 1253320603 -0700
committer John Wang <johnwang@google.com> 1253479238 -0700

Add ring back tone notification.

Some networks may not play ring back tone, RIL will send UNSOL ringback notification.

Apps can register for ring back tone msg and play tone to user for receiving ALERTING message.

The return value indicates to play or stop ring tone.