Network Change Monitoring

To monitor network changes you add a listener for the NetworkInfoEvent.CHANGE event and then handle the change in your event handler.

NetworkInfo.networkInfo.addEventListener( 
        NetworkInfoEvent.CHANGE,
        networkChangeHandler 
    );

private function networkChangeHandler( event:NetworkInfoEvent ):void
{
    trace( "isReachable=" + NetworkInfo.networkInfo.isReachable() );
    trace( "isWWAN=" + NetworkInfo.networkInfo.isWWAN() );
}