How to change/create SIM PIN using AT commands when the SIM card has no PIN?

Question

I'm using a SIM868 module and I was using my usual SIM card with no problem, but now I have bought a new SIM card and has no pin. I need to add a PIN code in order to have more security.

I have checked that it has no PIN enabled using this command: AT+CPIN? .

and the answer was: +CPIN: READY .

I have searched how to change it in the SIMCOM's AT commands manual and I have found 2 options:

1. AT+CPIN=<pin>[,<new pin>]
2. AT+CPWD=<fac>,<oldpwd>,<newpwd>

I have tried both of them, but in the first one I can't insert the actual PIN, because there is no actual PIN. And in the second one I have tried different commands due, in the description of the AT command, sais "If an old password has not yet been set, oldpwd is not to enter" . None of this ones has worked (guess that 1234 is the new PIN that I want to use)

1) AT+CLCK=“SC”,"1234"
2) AT+CLCK=“SC”,,"1234" 
3) AT+CLCK=“SC”,“”,"1234" 

The answer to that 3 cases was the same: ERROR .

(If someone is going to suggest that I can change or try the SIM card with a mobile phone I can't do it because this new SIM card is a miniSIM card and all my phones use nanoSIM or microSIM).

Any suggestions?

Answer 1

TL;DR

In order to set the PIN code 1234 you need to provide the following comment:

AT+CLCK="SC",1,"1234"

---

Explanation

As you correctly wrote, AT+CLCK is the correct command to enable/disable any module's facility, included "SIM PIN request". But your syntax is wrong.

According to ETSI specification , the correct syntax is

AT+CLCK=<fac>,<mode>[,<passwd>[,<class>]]

Where:

• <fac> (string) is the facility to be locked/unlocked ( "SC" in case of "SIM (PIN request)" ).
• <mode> (integer) is the operation to be done on the facility. This parameter was missing in your attempts .
  • 0 to unlock
  • 1 to lock
  • 2 to query lock status
• <passwd> is the password set with +CPWD (in your case it should be the PIN code but it is probably not required since it is not set).
• <class> is a sum of integers each representing a class of information. You don't eed it for your task.

---

Note: in development phase, when "playing" with AT commands, I suggest enabling verbose errors mode providing either AT+CMEE=1 or AT+CMEE=2 according to what your device do support (check it by providing test command AT+CMEE=? ).