Now the 2nd problem is of getting an 'OK' response. Even if i am able to send 'AT' to the modem ( which i can easily verify by communicating with COM port of PC ) i am not able to receive 'OK' response... even at 9600 baud. Also if i try to dial the modem by command
'ATDP215' ( 215 being the extension no. ) i don't get any carrier detect signal or no dialing tone can be heard. i've used the polling method for transmitting and receiving the character.

Post your code here probably that's the only way left to kill the bug.

Regards,
Prahlad Purohit