Getting the status of the phone

I have a remote service wich my phone is talking to. When Application_Deactivated gets called it doesn't have enough time to 开发者_如何学编程notify the service that is has gone into 'tombstoned' state. How can my service know wether the device is active or tombstoned?

Edit: I could imagine polling the service with my phone and when the service doesn't receive any events it will set the phone's status to tombstoned. But that would mean a massive increase in traffic.