COM.GSM Module

jorge5a

Hi:

I have attached a COM.GSM to my M5stack basic.
I can communicate with at commands but I can't send SMS or to do any GSM communication
It likes as the SIM can't connect with operator. I have tested with 3 SIM and I have tested all SIM's on a smartphone for sure that works fine. All SIMs I have tested have desactivated PIN security.
The GSM module blinks a blues led every second, as not registred

Could you help me?

Thanks

felmue

Hello @jorge5a

the COM.GSM can only operate with 2G networks. Are you sure in your region 2G is still operational? The fact that the SIMs work in a smartphone doesn't automatically mean they work in the COM.GSM as the smartphone could connect using something else than 2G.

That said you can try the following command. This will tell you if the modem has registered with a provider.

AT+COPS?
  +COPS=0 // auto mode not registered
  +COPS=1 // manual mode not registered
  +COPS: 0,0,"CHINA MOBILE" // auto mode registered

Or try to get a list of available providers.

AT+COPS=?
  +COPS: (1,"Sunrise","Sunrise","22802",0),,(0,1,2,3,4),(0,1,2)

Note: this command can take a long time and sometimes you need to issue it multiple times to get a result.

Thanks
Felix