I found a few posts related Azure notification hub support on PushKit VoIP notifications:
https://social.msdn.microsoft.com/Forums/ie/en-US/afda14fe-1218-4ca1-a1ee-205ccd241d1a/support-for-apple-voip-pushkit-push-notifications?forum=notificationhubs
https://social.msdn.microsoft.com/Forums/azure/en-US/39b4e1cd-842f-4562-bab5-119d5f6175cd/send-ios-voip-pushes?forum=notificationhubs
Does GCM works with iOS PushKit framework?
There's no official confirmation of the support, I did try myself by using same APN HTTP/2 configuration on my notification hub which you can use for either APN Notifications or PushKit VoIP Notifications but always got invalid token on registration to notification hub.
Have anyone make this work with Azure notification hubs? Is there support for this or not?