Update:
It has been recently announced that the changes that Apple would make to the iOS notification architecture after iOS 11 will not currently affect Jabber notifications for IM and calls for customers that have not yet upgraded their infrastructure to support Apple Push Notifications (APNs). However, it is still recommended to upgrade.Push Notifications are required both for Cisco Jabber for iPhone and iPad clients that connect from within the enterprise network as well as for clients that register to an on-premise deployment via Expressway's Mobile and Remote Access (MRA) feature.