I've read this topic http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj206983%28v=vs.105%29.aspx
And my knowledge I understand is that Server will send a Raw Notification ( with X-Class = 4 ) to Front-End(Windows Phone apps). Assume that my app is deactivate(it means that my device is on Lock Screen). And my question is how to make a VoIP incoming call(on client side) when Server send a Raw Notification to my WP device? To make another VoIP application, which functions or module do I have to consider in this project? I want to create an application that is same as Skype or Whatapps. Please help me. Thanks in advance!