SIM cards can be locked with a PIN.
SIM (Subscriber Identity Module) cards are used to store sensitive subscriber information. A SIM card connects your GSM- or iDEN-based mobile phone to your carrier's network and can also store your important phone book contacts. You can lock your SIM card to protect it from unwanted use by setting a PIN. Multiple wrong entries of the SIM PIN will require you to enter a PIN Unlock Key, or PUK.
Instructions
1. Enter the default PIN on the "Enter PIN" screen--if the SIM has been locked, this message will appear as soon as the phone is powered on. (The default PIN is set by your carrier--it is often "1111" or "1234.") If you receive a "Code Invalid" message, proceed to Step 2.
2. Re-enter the default PIN and press "OK." Repeat. (Three incorrect entries will prompt you to enter a PUK.)
3. Contact your wireless carrier and request the PUK for your device. You'll need to verify your account details before the code is released. (Have your security code handy if your account is password-protected.)
4. Enter the PUK and press "OK."
5. Enter a new PIN of your choosing. (The code must be four to eight digits long.) Re-enter the PIN when prompted to confirm and press "OK." Your SIM is now unlocked.
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