title: Callback for kAudioSessionProperty_AudioRouteChange not called in one case
body: <p>I want to be notified if headphones are plugged in or plugged out. I'm currently doing this using a property listener like this:</p>
  
  <p>AudioSessionAddPropertyListener (kAudioSessionProperty_AudioRouteChange, myCallback, self);</p>
  
  <p>This works perfectly well in all cases except in one, it goes like this:</p>
  
  <ol>
  <li>Launch, iPhone is unmuted, no headphones plugged in</li>
  <li>Switch the mute button on: The callback is called, good</li>
  <li>Plug in the headphones now: Callback is not called, not good</li>
  </ol>
  
  <p>Is there another property I should consider? Is there a special case involving the mute button I'm not aware of?</p>
  
  <p>I'm using an iPhone 3GS and iOS 4.1.</p>
  
  <p>Thanks a lot for any help!
  Patrick</p>