Can I make system services for windows phone? If yes then How? I am trying to make a system service that shows a messagebox everytime the phone is started , how to do this?
You can't make system services on Windows Phone. The best you can do is a background agent, that will be executed once every 30 minutes. You can also, on Windows Phone 8, use the GeoLocator to keep your application alive in the background (it's supposed to be used only for position-tracking purpose though). But none of these workarounds allow you to react to system events, like the phone startup.