Xamarin, C#: Getting Push-Notifications, even when the app is killed : I am asking this AGAIN, because all answers seem to regard Java and not C#. So please, only answers in C# ;-).

Our app uses a server that can send out push notifications to a phone. But it can only do that, while the app is at least in the background. As soon as it is killed as a background task ( from the task manager) the notifications will no longer be delivered. But how is for instance WhatsApp doing that? When I am closing whatsapp from the task manager, I still get notificated about incoming messages. 

Well, I though maybe a background service would help me out so this is what I have done so far:

        private void StartServiceForPushs()
        {
            Intent intent = new Intent(this, typeof(Activity_MainMenu));
            PendingIntent pendingIntent = PendingIntent.GetService(this, 0, intent, 0);
            AlarmManager alarm = (AlarmManager)GetSystemService(Context.AlarmService);
            alarm.SetRepeating(AlarmType.RtcWakeup, TimeUtils.CurrentTimeMillis(), 1 * 60000, pendingIntent);

        }

This should set up a service that checks for push notifications every 1 minute - but unfortunately, it does nothing. As soon as the app is closed completely, there are no more incomming messages. Can anyone help me out here?

Thanks!