title: Track a phone call duration
body: <p>Is it possible to utilize the users phone through their cell provider, and track the length of a phone call?</p>
  
  <p>So the user presses a button in the app "Call Now". A call begins to a pre-determined number. We record the start time. When the call ends, we calculate how many minutes were used.</p>
  
  <p>Possible?</p>