How to enter the PUK using AT codes

How to check if the SIM card requires a PUK input

First, verify if a PUK is needed using AT+CPIN?:

input: AT+CPIN?
output: +CPIN: SIM PUK
          OK

The output should be +CPIN: SIM PUK if the SIM card expects a PUK.

Enter the PUK and set a new PIN

If your PUK is 1112233 and the new PIN is 1234, the AT code to set the PUK is

Double-check that the PUK is correct, as entering it wrong too many times will lock the SIM card permanently!

AT+CPIN="11122233","1234"

This will respond with OK if successful:

output: OK