Hye Santosh,Refer the

[Vara Ashishkumar]

Hye Santosh,

Refer the following similar link for interface GSM module with atmega 8 :

http://www.engineersgarage.com/contribution/how-to-interface-GSM-SIM-300-modem-with-atmega32-to-send-and-receive-SMS

Note: Above link suggest for atmega32 and you want for atmega8 but no any difference between atmega 8 and atmega 32 expect memory.