The first link up there I posted mentions SMS which has too many meanings. Sametime Messaging Service, text messages or a service provided by Microsoft which is used for desktop management in an infrastructure setting. Sametime uses it's own client and protocol. SMS (text) uses the phone number to IP translation on the provider network. SMS (desktop management) uses the AD - DHCP translation acquired when the machine logs on to the server.
So, surveying these systems, PNS probably has a client application that uses it's own protocol to phone home to a server at Apple so that when the App Store has an update for one of your applications, it gets pushed to you and the others who own the app but not those who do not. That would seem the most likely way to avoid the problems you point out with IP changes, or rather, to take them into account.
Short on details, PNS appears to be built into iOS as far back as iPhone 3.
http://www.tipb.com/2009/03/17/apple-announces-push-notification-services-iphone-30/
The first link up there I posted mentions SMS which has too many meanings. Sametime Messaging Service, text messages or a service provided by Microsoft which is used for desktop management in an infrastructure setting. Sametime uses it's own client and protocol. SMS (text) uses the phone number to IP translation on the provider network. SMS (desktop management) uses the AD - DHCP translation acquired when the machine logs on to the server.
So, surveying these systems, PNS probably has a client application that uses it's own protocol to phone home to a server at Apple so that when the App Store has an update for one of your applications, it gets pushed to you and the others who own the app but not those who do not. That would seem the most likely way to avoid the problems you point out with IP changes, or rather, to take them into account.