Zte Z557BL User Manual page 31

Encryption provides additional protection in case your phone
is stolen, and may be required or recommended in some
organizations. Consult your system administrator before
turning it on. In many cases the PIN or password you set for
encryption is controlled by the system administrator.
Before turning on encryption, prepare as follows:

Set a lock screen PIN or password.

Charge the battery.

Keep the phone connected to the charger.

Schedule an hour or more for the encryption process. You
must not interrupt it or you will lose some or all of your data.
When you're ready to turn on encryption:
1. Press the Home Key >
phone.
2. Read the information about encryption carefully. The
ENCRYPT PHONE button is dimmed if your battery is not
charged or your phone is not plugged in. If you change your mind
about encrypting your phone, press the Back Key.
WARNING! If you interrupt the encryption process, you will lose
data.
3. Tap ENCRYPT PHONE.
4. Enter your lock screen PIN or password and tap NEXT.
5. Tap ENCRYPT PHONE again.
> Settings > Security > Encrypt
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