The question has been asked many times: what is this PUK code my phone is asking for? Where did it come from? How do I find the code? The PUK code stands for Personal Unblocking Key. If you see it pop up, don't freak out! It is designed to protect your phone from unwanted users, and there is a way to find out what the code is.

For example, when you set up PIN codes to block people from certain applications from your phone, if someone tries to get in and puts in the wrong code 3-5 times, it prompts that person for the PUK. The only way to get the PUK is to either call your cell phone provider or visit the local corporate-owned store and verify the account information. Putting in the wrong PUK code 3-5 times will permanently block your SIM card from further use. At that point, the only option is to go into the local store and replace your SIM card completely in order for your phone to work. Your old SIM card will never be functional so any numbers you had stored on the card can never be accessed again.

When you put in the right PUK code, the phone will prompt you to change your PIN code to something new so that you can remember it more easily.

Thus, the PUK code protects your phone from phone thieves or a nosy younger brother.