I am using an Arduino UNO and a SIMCOM SIM900 GSM/GPRS Shield And my code works.
However when I open the serial monitor I get this message:
Trying to force the baud-rate to 9600
ERROR: SIM900 doesn't answer. Check power and serial pins in GSM.cpp
Could it maybe be the SIM Card I am using? I am using a TMOBILE SIM Card. ANd when I put it in the holder, I get a blink every second from the NetLight meaning its not connected. What sim card should I be using. I live in the USA