Learn how to use SIM card lock on your Samsung Galaxy S4 Active. Prevent another user from using your SIM card to make unauthorized calls or from accessing information stored on your SIM card by protecting the information using a PIN code. When enabled, your phone will ask for a PIN number each time you use the phone. Using this option you can also change your SIM PIN number.
Note: You must activate Lock SIM card before you can change your SIM PIN code.