The previous generation handsets will not support turn-by-turn navigation or 3D flyover functionality in the Maps application, or be able to run Facetime over a 3G connection.
iPhone 4S, iPad 2 and third-generation iPad devices will be fully compatible with all of the features of Apple's forthcoming mobile operating system.
iOS 6 was unveiled during Apple's Worldwide Developers Conference earlier this week. One of the biggest talking points of the evening was the inclusion of Maps, which sees new battle lines drawn between Apple and Google.
The TomTom-powered service will replace Google Maps as the pre-installed mapping application on iOS devices, a significant blow for the search engine giant.
iOS 6 will be rolled out in the autumn.
Picture gallery - Apple's Worldwide Developers Conference announcements:
Copyright: Paul Sakuma/AP/Press Association Images