You must be joking...what's the 2G/3G has to do with the ringtones ? I would try to stop the accelerometer...the one that lowers the ringtone sound when u pick it up.
Check out this thread. The issue is not because of the accelerometeri also have Legend india version.i also facing this ringing problem. i have disabled the accelerometer which lowers the ringtone. even then it gets muffled after 10 or 20 seconds automatically. but i dnt have any issues listening songs. please help! i tried many setting bt no luck...