LG -P700 Guide De L'utilisateur page 301

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.
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