Re: What is incallui app mainly used for
In call UI, is a system app that is the interface (User Interface =UI) between you and your device. It's the interpreter between your button push and the machine. When you tap your screen in a certain place, it tells your phone to hang up. When you hold it to your ear, it turns off the screen digitiser so your face touch doesn't do anything and many other jobs like that. These are all system programs that are necessary for the device to function and not a sign of your husbands infidelity.
Perhaps talking to him instead of snooping in his phone may be a better way to resolve it.