Zte T230 User Manual page 63

UNLOCK THE SCREEN WITH A PATTERN
 Press Power Key.
 Draw your pattern to unlock the screen. If you make a mistake you can
try again up to five times.
If you forget the unlock pattern then after five attempts you can enter
your Google account details to unlock your device.
SET A SIM CARD PIN LOCK
 Set a PIN code on your SIM card to prevent others from using your
account.
 The initial PIN code is provided by your service operator.
 Tap Options > Settings > Security > Set up SIM card lock.
 Select Lock SIM card. Enter the PIN and tap OK.
CHANGE SIM PIN
Before changing the SIM PIN, you need to enable it.