Muralikrishna, try using SIM900 series GSM modem, they are quite easy to interface with any controller, and they have inbuilt HTTP / FTP commands, so from controller point it relives us from TCP/IP stack on the controller.
I think I have a circuit diagram for this GSM with Mega32 i suppose. let me search my system and if lucky to find then i will share it.
~SwK.