Nokia 6316s-1 User Manual page 115

When the keypad is locked, calls still may be possible to
the official emergency number programmed into your
device.
To lock the keypad automatically when no keys are pressed
for a certain length of time, in the standby mode, select
Menu > Settings > Phone > Automatic keyguard > On.
To lock the keypad in the standby mode, close the slide,
and select Lock.
To unlock the keypad, open the slide or select Unlock, and
select OK within 2 seconds.
If you receive a call when the keypad is locked, it is
automatically unlocked, and then locked again when
you end the call.
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