Apple has deliberately, and quite craftily so, shaped a paradigm where Siri AI's most powerful features will only be available on the Pro iPhones from now onward, which only serves to add another demand-related tailwind to the upcoming iPhone 18 Pro and Pro Max, while subduing the expected uptake of the low-margin and high-volume base iPhone 18 variant.
Siri AI's premier functionalities now require a double-digit RAM, which should skew Apple's upcoming sales mix to favor the iPhone 18 Pro models
As we detailed in a dedicated post, the all-new Siri AI and Apple Intelligence is powered by 3 cloud-based models, with the AFM 3 Cloud Pro reportedly distilled from a 1.2-trillion-parameter Google Gemini model, and two on-device models, called AFM 3 Core Advanced and AFM 3 Core, respectively.
While the AFM 3 Core has just 3 billion parameters, the AFM 3 Core Advanced takes the parameter count to 20 billion, but only activates between 1 and 4 billion parameters at a time, depending on the task at hand. Critically, it is this model that unlocks a revamped dictation function and more expressive Siri AI voices.
At a granular level, Apple's AFM 3 Core Advanced sports an innovative architecture, where model attention blocks - which look at the broader meaning within a given prompt - reside in the DRAM, while Feed-Forward Network (FFN) weights - which explore each prompt string or word individually to surface its specific meaning within the given context - reside in the NAND.
Even though Apple's AFM 3 Core Advanced model only loads between 1 and 4 billion parameters into the DRAM at any given time, it still requires a RAM size of at least 12GB, which seemingly eliminates the base iPhone 18 as a viable vector for this model, given the variant's expected 8GB RAM size.
Of course, Apple could have feasibly engineered its AI architecture to unlock the advanced dictation and the more expressive Siri voices on the base variant as well by relying more heavily on its cloud-based models. Yet, the Cupertino-based tech giant has not done so, which only serves to increase the attractiveness of the upcoming iPhone 18 Pro models relative to their base counterpart.
About the author: Writing is my one incontrovertible passion. Over the past six years, he has authored over 2,200 distinct articles on financial and tech-related topics, spanning nearly 1 million words. And he has been a member of Wcctech mobile team since 2025. As an alumnus of the University of Toronto, Rotman Commerce Program, I bring nuance, in-depth knowledge, and a unique perspective to every topic that I cover. When I'm not writing, I'm traveling the world, exploring hidden confectionaries and restaurants as an aspiring food connoisseur.
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