When is APNs used?

Apple Push Notification service (APNs) is used when a Voalte app is terminated. A socket connection is kept open on Voalte One directly to the Voalte Platform Server, and it is severed by the device if the app is terminated, usually when it is force-quit by the user or it crashes. Then, Voalte Platform utilizes APNs to ensure notification delivery to the device.