The SIM card is protected by a PIN code.
When prompted for the number of PIN entry attempts (AT+CSIM=10,“0020000100”), the card resets to the “PIN CODE” state, even if the correct code was entered.
Subsequent attempts to enter the correct PIN result in error 16.
ati
Quectel
RG500U-EB
Revision: RG500UEBAAR03A09M4G
OK
at+cfun?
+CFUN: 1
OK
at+cpin?
+CPIN: SIM PIN
OK
at+cpin=0000
OK
+QUSIM: 1
+CPIN: READY
+QIND: PB DONE
+QIND: SMS DONE
at+cpin?
+CPIN: READY
OK
AT+CSIM=10,“0020000100”
+CSIM: 4,“63C3”
OK
at+cpin?
+CPIN: SIM PIN
OK