The main discussion this year among Apple fans has been the exclusivity of Apple’s "most powerful on-device model", known officially as Apple Foundation Models (AFM) Core Advanced. Only three iPhones — the iPhone 17 Pro, iPhone 17 Pro Max, and iPhone Air — have enough RAM (12GB) to access this model and, therefore, the very best version of Siri AI. But what does that mean, exactly?
According to Apple’s press release on Siri AI, the two features exclusive to AFM Core Advanced are voice customization and more advanced systemwide dictation.
That means iPhone 16 Pro owners will not get two features that depend on the model: more expressive Siri voices and a major accuracy improvement for system-wide dictation.
voice customization gives you the ability to customize the expressiveness and pace of Siri’s voice — anyone with access to Siri AI can still choose from a set number of Siri voices, but the iPhone 16 Pro doesn’t support this feature. According to Apple, you’ll need an iPhone 17 Pro, iPhone 17 Pro Max, and iPhone Air to make Siri speak faster, slower, and with more or less enthusiasm.
The second Siri AI feature missing on the iPhone 16 Pro — more advanced systemwide dictation — is arguably the more significant. It essentially means those top-end iPhones are more effective at converting speech into accurate text than older or less advanced iPhones. This updated dictation engine "automatically handles capitalization, punctuation, and formatting as [you] speak," Apple says, meaning you can "speak naturally and trust that [your] words will appear clearly, accurately, and as intended".
To be clear, this doesn’t mean that Siri on your iPhone 16 Pro will be incapable of converting speech into text. Yes, Siri has been awful at doing just that in the past — anyone who’s tried to send a message using CarPlay will know what I’m talking about — but my understanding is that Siri AI, in being an entirely new version of Siri, will bring improved dictation at a foundational level (i.e. to all compatible iPhones).
But for those who rely on dictation to send messages or navigate their iPhone hands-free, the difference in dictation capabilities between the best iPhones and older models may be more consequential.
At the moment, owners of the iPhone 17 Pro, iPhone 17 Pro Max, and iPhone Air are simply getting a more customizable Siri, and one more capable of converting speech into text.
Related: Why the iPhone 17 Doesn’t Get Every Siri AI Feature
That’s not ideal for iPhone 16 Pro or iPhone 16 Pro Max users who thought they were buying a phone “built for Apple Intelligence” — lawyers at the ready! — but, everything else in iOS 27’s Siri AI rollout — personal context, onscreen awareness, web answers, the dedicated Siri app, Visual Intelligence, and Writing Tools — runs on the broader Apple Intelligence device list. That list still includes iPhone 15 Pro, the iPhone 16 series, and iPhone 17.
The 12GB requirement, in other words, does not refer to Siri AI wholesale, but improves how Siri sounds and how well it transcribes. The iPhone 16 Pro owners will still get the new chatbot-style assistant with iOS 27, they’ll just get the older voices and a less precise dictation engine.
Of course, in classic marketing fashion, Apple’s small print on the matter leaves the door ajar for more features to be made exclusive to the AFM Core Advanced model: “Apple’s most powerful on-device model and the features it enables, like expressive voices and more advanced dictation, are available on…,” reads the press release. ‘Like’ is the operative word there — more hardware-exclusive features are surely coming down the line, ones which require more compute power than Apple’s base AFM Core model can provide.
