Hello umb, thanks for your question
Regarding the module is not registered to the network, please try the following steps:
Re-plug the SIM card and execute AT+CPIN? to check the SIM status
Execute AT+CREG? to check whether the return value is 0, 1
Power off and restart the module and repeat the above steps
If it still does not work, please confirm whether the antenna is connected properly, whether the SIM card is in arrears, and whether the test site is covered by the operator’s network.