In the middle of phone calls, the phone will vibrate or jolt and the screen brings up the phone menu where I can dial new numbers and such. The other call is still going and I can hear that person but they cant hear me. Only way to get the call back so they can hear me is by clicking on it through the notifications. It seems as if my face pressed against the phone might be hitting buttons? I am unsure of the cause but is there anyway to lock the screen during a phone call so that other buttons are not being pressed? Any other tips or suggestions would be greatly appreciated.