Problem connecting Arduino Uno R3 to SIM900 GPRS/GSM shield and sending an SMS

Right, similar module to yours. D7 - D7, D8 - D8, Gnd - Gnd, 9v 1A psu for testing module, USB supply to Uno:

Connect using serial monitor:

ScreenCap.jpg

I dialed my cell (mobile) phone and it connected.

ScreenCap.jpg