How to Unlock a Cell Phone SIM
The Personal Unblocking Key (PUK) is an eight-digit code that unlocks a locked cell phone. If you have purchased a locked cell phone or want to change carriers, you need to have the PUK code in order to unlock the SIM card. You can contact your service carrier and ask for the PUK number to unlock your phone.
Call your cell phone carrier and ask for the PUK code. In most cases, you need to have an account in good standing for 90 days before they will provide you with one.
Unlock the SIM card on your phone using the PUK code provided by your carrier. If you need help doing this, contact your service provider or log in to your account on the carrier's website and click "Support."
Enter a new PIN number. You will be prompted by your phone to enter a PIN number after you input the PUK code. You need to enter it a second time to confirm.
Power off your phone and turn it back on. The SIM card is now unlocked.