1Open Screen & Lock 
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2Under Voice Dialling, tap On or Off next to Enable When Locked.
Sounds & Ringtones
Use the ringer switch
Sliding the ringer switch off (red means off) not only turns off the ringer for incoming phone calls, it also turns off system sounds like the Calendar notifications and the camera shutter click when you take a picture. The ringer switch does not affect music and video sound.
By default, when the ringer switch is off, you can still hear the Clock alarm. If you want to change this setting so that turning off the ringer switch also turns off the Clock alarm sound, go to Clock > Preferences. Under Ringer Switch Off, change Play alarm anyway to No. If you set this option to No, be sure to change it back to Yes the next time you set an
Set ringer switch settings
You can set how your smartphone treats system sounds and rings for incoming calls when the ringer switch is off and when it is on.
1Open Sounds & Ringtones 
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2In Ringer Switch Off > Rings & Alerts, tap the currently displayed option, and then tap an option to set what happens when the ringer switch is off and a system sound or the ringer would normally play. Tap Vibrate to have your smartphone vibrate instead of playing the sound. Tap Mute to have nothing happen.
3Under Ringer Switch On > Rings & Alerts, tap the currently displayed option, and then tap an option to set what happens when the ringer switch is on and a system sound or the ringer plays. Tap Sound & Vibrate to have your smartphone both play a sound and vibrate. Tap Sound to have your smartphone play a sound only.
Set system sound options
You can turn system sounds, such as transition sounds and notification alerts, on or off. You can also set the volume for system sounds.
System sounds are turned on by default. Your smartphone plays your system sound only when the ringer switch is on.
Chapter 13 : Preferences 181