iOS - best practice to send incoming call notifications on VoIP app

Question

The first solution I can think of for the incoming call notification is Apple\'s Push Notification service. However, it is not guaranteed.. there\'s a relatively high chance it

Answer 1

Just play a very long duration audio when a APNS comes.

Answer 2

From appleDoc Apple Developer Docs. (Updated link)

In iOS 8 and later, voice-over-IP (VoIP) apps register for UIRemoteNotificationTypeVoIP push notifications instead of using this method. Using push notifications eliminates the need for a timeout handler to check in with the VoIP service. Instead, when a calls arrives for the user, the VoIP service sends a VoIP push notification to the user’s device. Upon receiving this notification, the device launches or wakes the app as needed so that it can handle the incoming call.