Unity VR on Android 10: incoming call message suppressed; “overlay” as well

I noticed the following problem: when a Unity app is running in VR mode on Android 10 (at least, on my Samsung Galaxy S9+): I get no message when the phone is called. Why is this the case, and how can it be circumvented?

My actual problem is slightly different: working on an app which displays an overlay over other apps. This is working fine on several devices running Android 5-9. It is also working on Android 10, but not for all apps - in particular, it is not working over one particular VR game.

In analyzing the problem, I found two interesting pieces:

a) I also get no incoming call message at all while in the game (neither when incoming calls should be displayed as a notification or as full-screen. Only difference: if incoming-call-message is set to full-screen, then the sound of the game stops - but still no ringtone)

b) in trying to understand this behavior, I found that "full screen activity" is a way of suppressing incoming call messages. Does Unity VR start as a "full screen activity"?

There are two possible solution-paths:

1) (preferred: ) can I set my app to have sufficiently high priority so it gets displayed on top of the other app in any case?

2) How can the unity app avoid being this dominant - can one start Unity VR mode with less "full screen" requirement? I found that I can write a 2d-unity app which lets itself be overlayed, and which signals incoming calls. It also seems "fullscreen" to me, i.e. notification bar and android system buttons are hidden.

 

Hi all,
we made some progress - or rather, got some new insights that contribute to the confusion. Still very happy when someone has some knowledge to share!

• there are Android-10-based phones where the overlay works as expected -> so we may have to look deeper into Samsung specifics
• on Samsung Galaxy S10, running Android 9, the overlay also works as expected.
• There are other apps on which the overlay does not work. Example: the "settings" app: when overlay is turned on and you switch to "settings", then the overlay disappears. However, incoming call-message comes through on top of "settings".

So the question is: what does Unity VR do to become more prominent than overlays, on Galaxy S9?