Lock or unlock your display, set a screen passcode or Touch ID, get your devices PUK code, or request your device be unlocked from the AT&T network.
INSTRUCTIONS & INFO
If your device does not have a passcode, press the Home button to unlock your device.
Set a passcode on your iOS device to help protect your data. Each time you turn on or wake your device, you'll need to unlock it with your passcode. To set or change your security lock, from the home screen select Settings. Note:If you turn Passcode on, you’ll be asked to enter your passcode when you: Turn on or restart your device, Press to unlock your screen (you can change this), Update your software, and Erase your device.
Select Touch ID & Passcode. Note:On devices without Touch ID, go to Settings > Passcode.
Select Turn Passcode On. Note:If passcode settings are unavailable, gray, or dimmed and you can't change these settings, it might be because you're using a configuration profile that requires a passcode. This is common with business or education devices. Contact your IT administrator for more information.
For additional security, select Passcode Options and set a Custom Alphanumeric or Custom Numeric Code.
To add a fingerprint for Touch ID, go to Settings > Touch ID & Passcode > Add a Fingerprint... and follow the prompts. To register additional fingerprints, select Add a Fingerprint... again and repeat the process for up to 5 fingerprints total. Note: Learn more from Apple support article: Use Touch ID on iPhone
To deregister or edit a fingerprint name, select Desired fingerprint.
To edit, enter the Desired name then select Done. To deregister, select Delete Fingerprint.
Select the Desired features you would like to use Touch ID for.
To allow access to features when iPhone is locked, scroll down and select Desired features.
To erase data after ten failed passcode attempts, select the Erase Data toggle. After ten failed passcode attempts, all settings are reset, and all your information and media are erased by removing the encryption key to the data. Note: When prompted, select Enable.
To allow access to Control Center when iPhone is locked, go to Settings > Control Center and select the Access on Lock Screen toggle. Note: To learn more about requesting a device unlock for your AT&T mobile device, visit att.com/deviceunlock. If your device is locked and is requesting a "PUK" code, click here for instructions on how to obtain your PUK or PUK2 code to unlock your SIM card.
To adjust the lock screen timeout setting, go to Settings > Display & Brightness  then select Auto-Lock and you'll be prompted to choose a Desired option.
To lock the device screen, press the Sleep/Wake button.
To unlock the device screen, press the Home button with a Touch ID-registered finger. Note: If using a passcode instead of Touch ID, press either the Sleep/Wake button or the Home button then enter your passcode to unlock the device.