Background Location Updates in iOS

Background Location Updates in iOS

I've been working on a location-based app, and at this point everything is
working except for when the app is in the background. I've set the
appropriate plist string and I definitely begin monitoring the location
before it goes to the background, so I'm not sure why it isn't working.
Three things should happen when the location is updated: a string should
be created with the information about the user's whereabouts, that message
should be sent to a Java server using socket connections, and the server's
response should be read aloud using OpenEars. All of this works when in
the foreground. What could be causing this?
Thanks!