title: Android PhoneStateListener is not working in sleep mode
body: <p>I'm writing an app, which listens to GSM signal strength. I've created a service, in which I put the PhoneStateListener. The problem is, that PhoneStateListener does not listen to any changes while phone is in sleep mode. I really need to solve that problem, could anyone help me with this?
  I tried to use that code in onCreate() method:</p>
  
  <pre><code>PowerManager pm = (PowerManager) getSystemService(Context.POWER_SERVICE);
  wakeLock = pm.newWakeLock(PowerManager.FULL_WAKE_LOCK, "call_lock");
  wakeLock.acquire();
  </code></pre>
  
  <p>but it doesn't solve my problem, listener is still not listening in sleep mode.</p>