title: onCallStateChanged() method failed to give incomingNumber
body: <p>I have created a call recording application and wants to save the recorded audio file with the incomingNumber which is the argument of onCallStateChanged() method but it's not providing any incomingNumber. What's going wrong.</p>
  
  <p>I'm Using Android Studio and HTC Desire C as testing device.</p>
  
  <p>Thanks in advance.</p>
  
  <p><strong>Code</strong></p>
  
  <pre><code>@Override
      public void onCallStateChanged (int state, String incomingNumber)
      {
          Log.d("MyLogs", "state:" + state + " incomingNumber:" + incomingNumber); //incomingNumber is empty.
  
          switch (state) {
          case TelephonyManager.CALL_STATE_IDLE:
              ...
          }
      }
  </code></pre>