When your phone is lost or stolen, others can use your phone number and verification code, leaving your accounts and personal information vulnerable. For instance, your photos or chat records may be leaked, or your personal information can be used by others to make financial transactions.

A PIN serves as the SIM card's identity code, and can be used to protect the SIM card. Once it has been set up, you will be required to enter the correct PIN to unlock the SIM card each time that you power on your device or switch to a new phone, to prevent unauthorized access.

If you have entered an incorrect PIN, and exceeded the maximum number of unlock attempts, you will need to enter the PIN Unlocking Key (PUK), and then reset the PIN. If you exceed the maximum number of attempts allowed to unlock the PUK, your SIM card will be permanently blocked.

The initial PIN and PUK associated with your SIM card are provided by your carrier. The number of digits and maximum number of unlock attempts allowed are subject to your carrier.

1. Go to Settings > Security > SIM PIN to enter the SIM PIN screen.

2. Enable SIM PIN, enter the PIN, then touch OK.

   To change the PIN, touch Change SIM PIN, and follow the onscreen instructions.