Enter the default PIN code. This code is determined by your carrier, and is usually "1111" or "1234." If these codes do not work, continuing entering incorrect codes. Three incorrect code entries will prompt you to enter a PUK (PIN Unlocking Key) code.
Contact your wireless provider to obtain your PUK code. You will need to verify your account details before your carrier will release the code to you. Make a note of the code.
Type the PUK code into your phone and press "OK." Your phone will then prompt you to enter a new PIN. The PIN can be any numeric code you desire. Type in the desired code and press "OK." Re-enter the code to verify, then press "OK" to finish unlocking your SIM card.