Question Apple IOS Callkit / Pushkit - VOIP Notification support?

Is there a way to configure a Unity app to work with Apple's Callkit/Pushkit to receive VOIP Notifications (as in the caller actually ringing with answer/reject buttons in the notification and a full screen native blowup of the call incoming).

Something similar to what Skype, Whatsapp etc do but we have a Unity app where users can call each other to arrange a session and simply sending regular notifications and having the app itself ring while the app is open isn't quite cutting it for initiating calls.

Interesting use case here but I cannot see any hint of where to start with such a matter

We are currently using OneSignal push notification SDK for Unity which does not support VOIP out the box with the Unity SDK but has hookups but we are not tied to their SDK at this time while we explore VOIP call ringing options from Unity.