Thank you, sir. But Sir, I need the ckt diagram too. I hv an AVR development board to which I think I hv to connect a RELAY CKT to control the motors. I hv written a tentative program too which controls the OUTPUT pins acc to HIGH or LOW signal received at Input pin. But I hv no idea abt how to connect the SIM900 wid the AVR Atmega 8 development board and make it interpret the sms commands like ‘1’ for ON & ‘0’ for OFF. Sir can u plz giv me the circuit diagram and the necessary componebnts that I need? Plz sir.