Deactivating screen during calls

[Ni]

Is there a way to deactivate the touch screen when I am on a call. My cheek keeps hitting it and either muting or disconnecting the call. The only solution I have found so far is to hit the power button after I answer a call. This is irritating though because I can't disconnect the call easily and can't view incoming calls.

Ideas?

 

[google123]

Is the proximity sensor enabled?

dial ##PROGRAM
SPC password is 000000 (six zeros)
option 10 proximity sensor, make sure its on...