LG -P715 Manual page 110

Getting to know your phone
Device components
NOTE: Proximity sensor
When receiving and making calls, the proximity sensor automatically turns
the backlight off and locks the touch screen by sensing when the phone is
near your ear. This extends battery life and prevents you from unintentionally
activating the touch screen during calls.
WARNING
Placing a heavy object on the phone or sitting on it can damage the LCD and
touch screen functions. Do not cover the LCD proximity sensor with protective
film. This could cause the sensor to malfunction.
18
Front-facing Camera lens
Earpiece
Proximity sensor
Power/Lock key
Switch your phone on/off by pressing and holding this key.
Short press to lock/unlock the screen.
Back key
Return to the previous screen.
Home key
Return to the Home screen from any screen.
SIM switch key
Switch between SIM1 and SIM2.
Touch and Hold the key to go to Dual SIM settings.
Menu key
Check what options are available.