title: Notification wakes up IOS and ANDROID app in xamarin
body: <p>I have application written in Xamarin that uses firebase.</p>
  
  <p>Imagine both apps( iOS and android) are killed and our phone is locked. Notification comes to the app ( iOS and android ) and I want to wake up one screen from my Xamarin app ( somebody is calling my app so it behaves like skype).</p>
  
  <p>How to achieve that? </p>