When i'm calling there are two sliders that gives me option to end call and/or go to another page that contains speaker on , keypad and etc... therefore i don't need the screen goes off and the phone become locked.
And this really drives me crazy to turn the screen on by pushing a key and then unlock the phone and after these all slide the slider to get the keypad to put the numbers i want.

anyone knows how i can prevent screen-off and phone lock while calling ?

PS :
No proximity sensor
cellphone: LGC660