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The phone lock code protects the contents of your phone from unauthorised use. When the phone lock code is turned on, it needs to be keyed in every time you turn on your phone and when it has been in sleep mode.
Find "Screen lock"
Press the settings icon.
Create phone lock code using a pattern, go to 2a.
Create phone lock code using a PIN, go to 2b.
2a - Create phone lock code using a pattern
Follow the instructions on the display to key in a back up code if you should forget the phone lock code.