A PIN Unlock Key or Personal Unblocking Key (PUK code) is a unique number that’s used to unlock the Subscriber Identity Module (SIM) card for your phone. The SIM card contains all the account details your phone needs to make and receive calls—including generated passwords, or PIN codes. If you forget or lose the PIN code, you can use the PUK code to unlock the SIM card. You will be prompted for the PUK code if you enter the PIN code incorrectly three times on your phone. You can get your PUK code from your carrier.
Browse to your carrier’s website and enter your account login, or follow the prompts to register. This will include entering details such as your telephone number, name and a password. The password on the website account is unrelated to the SIM card password.
Select “My Phone” or “About Phone” or something similar and look for a settings summary.
Enter the PUK code from the website on the phone when prompted to do so. The phone will prompt you after three incorrect PIN number attempts. You will have 10 attempts to enter the correct PUK code before your SIM card locks up and becomes unusable.
Enter a new four- to eight-digit PIN code when prompted to do so. The phone will prompt you after you have successfully entered the PUK code.
Re-enter the desired PIN code to confirm.
The default PIN code is often 0000 or the last four digits of your cell phone number.
If you fail to enter the PUK code correctly on the 11th attempt, the SIM card will stop working and you will have to get a new one.