@felmue Thanks a lot. This solved my project

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