I just got this SIM908 dev board, and I'm trying to get it working. However, it keeps telling me "SIM not inserted":
AT+CPIN? +CME ERROR: SIM not inserted
which of course causes other operations to fail:
AT+COPS=? +COPS: (1,"AT&T","AT&T","310410"),,(0,1,4),(0,1,2) OK AT+COPS=1,1,"AT&T" +CME ERROR: operation not allowed
I was trying to use the SIM card from my smartphone (StraightTalk on AT&T), and I also tried an unprovisioned AT&T SIM just to see if it was detected.
Could the problem be that the SIM card has the wrong application on it? Should USIM be backwards compatible with a 2G module?
Also, I don't know if this is related, but I noticed that just after power-up, SIM_VDD oscillates briefly at about 2MHz. I think that might be a normal part of the voltage detection process, but I'm not sure.
What should I need to get this working?