If you need to get data more frequently than the default available in Windows Phone, you should think about using push notifications. This won't be suitable for a full data push, but if you use it correctly, you can get a user experience that you can live with.
One common approach to this is to set up your server to send a notification to the device when there is something new to report instead of pushing a "nothing has changed" message every 10 minutes or so. If you push out a tile update notification to say, for example, "You have x unread items", the user may then click on the tile for your app and you can poll the server for new items on launch/resume. If you want a more intrusive option, you can send a toast notification as well, but in most cases the tile update will be sufficient.
This method has a few advantages.
- You won't be burning through battery power polling every 10 minutes while the user is asleep
- Your server will have significantly less load since it is not having to process full data requests every 10 minutes per client.
- This fits in with the design philosophy of Phone apps - you are surfacing the required data to the user, while at the same time preserving battery life.