How to hang up an outgoing phone call by clicking anywhere on screen
<p>I'm building an app for blind people. Part of it is that by clicking on a button it starts the phone app (calling a contact). How can I finish the call by clicking anywhere on screen (as the blind people don't have the ability to click exactly where the hang-up button is on screen). Or by hanging-up automatically after, let's say, 5 ringings. 
Is it possible?
Thanks!  </p>
