title: Can the android geofencing system (Google Play Services) trigger events when the phone is sleeping
body: <p>I'm trying to find out if the Google Play Services geofencing and location system can be practically used for background location monitoring.</p>
  
  <p>An example scenario is that I have the phone in my pocket, and enter a geofenced area - will the event handler in my app be triggered so I can deal with the event as appropriate, or is the system only intended to be used whilst the phone is awake and the app in the foreground?</p>
  
  <p>I've been banging away at the example code, and so far haven't managed to make it work in this way - or find docs fully addressing this - it seems to be too new for people to be using it much.</p>
  
  <p>Obviously the phone doesn't use GPS continually whilst sleeping, or the battery would run down quickly, but I'm wondering if the broad network location is monitored and used for this purpose (or to discover if the device is within short distance of a geofence, to know that it's worth polling the GPS periodically to find if it has been crossed.)</p>