title: How to block calls in android
body: <p>I want to block calls from few numbers, for that I want to write a app of my own.
  So what are the APIs which I should be using?</p>
  
  <p>Basically I want to get notified when a call comes, i want to compare numbers if it is what i want to block, i want to cut the call or mute it or if possible mute it and record it.</p>