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If use of phone lock code is turned on, it needs to be keyed in when you turn on your phone. Follow these instructions to change the phone lock code.
Find "Phone password"
Press the Menu key.
Press Change password.
Press Phone password.
Change phone lock code
Key in the current phone lock code (default is 0000) and press OK.
Key in a new phone lock code and press OK.
Key in the new phone lock code again and press OK.
Press Disconnect to return to standby mode.