For security, you can require a PIN code to use your SIM card in any device. This PIN code follows the SIM card from one device to another.
What is a SIM card lock?
A SIM card lock keeps your device from being used on any other network except yours. For example, if you have wireless service with us, then your SIM lock prevents someone else from using your phone on a different carrier. It’s a security measure. Your SIM card may be locked by the phone’s manufacturer when you get it.
Learn how to lock your SIM card
Want the steps to lock the SIM card for your device? Go to Device help and download the user manual for your device.
Enter a PIN code to lock your SIM card
When you enable SIM lock, your device asks you to enter a PIN code:
The default PIN code for an AT&T SIM card is "1111".
Change the default PIN code for more security.
After activating SIM lock, you must enter the PIN code if you move the SIM card to another device.