title: How can I determine if there is a call ringing on "line 2" (e.g. call waiting)
body: <p>I'm using an intent-filter to listen to changes in PHONE_STATE</p>
  
  <pre><code>    &lt;!-- Listen for phone status changes --&gt;
      &lt;receiver android:name=".IncomingCallReciever"&gt;
             &lt;intent-filter&gt;
                 &lt;action android:name="android.intent.action.PHONE_STATE" /&gt;
             &lt;/intent-filter&gt;
      &lt;/receiver&gt;
  </code></pre>
  
  <p>... and can easily detect an incoming call</p>
  
  <pre><code>       intent != null 
      &amp;&amp; intent.getAction().equals(TelephonyManager.ACTION_PHONE_STATE_CHANGED)
      &amp;&amp; intent.hasExtra(TelephonyManager.EXTRA_STATE)
      &amp;&amp; intent.getStringExtra(TelephonyManager.EXTRA_STATE).equals(TelephonyManager.EXTRA_STATE_RINGING)
  </code></pre>
  
  <p>... but how can I determine if it is line 1 or line 2 that is ringing? </p>
  
  <p>My application needs to react ONLY when the user is currently on a phone call and another call is coming in. </p>