The iPhone’s touch screen is designed to react to the lightest touch of your finger, which is great when you’re navigating apps but not quite as useful when you’re trying to talk on the phone. If you regularly mute or end calls by accidentally touching the iPhone screen with your face, you can prevent these mishaps by locking the screen during the call. The iPhone doesn’t support this functionality by default, so you’ll need a workaround. Tips Warnings

How to Lock an iPhone Touch Screen During Phone Calls - 81