Update (November 9, 2026): iOS 27 shipped on September 14, 2026, and the choice of Claude or Gemini that this page first described isn’t in it. Apple’s iOS 27 iPhone User Guide lists one outside AI for Siri, the ChatGPT extension, and no setting that makes another AI your default assistant. We’ve rewritten this page around what Apple, OpenAI, Anthropic and Google document today.
A few weeks before WWDC 2026, “you’ll be able to swap Siri’s brain for another AI” was a well-sourced rumor. On May 5, MacRumors relayed a Bloomberg report that iOS 27 would let you set a third-party AI service, Claude or Gemini and not just ChatGPT, as the default for Apple Intelligence features like Writing Tools and Image Playground. We first wrote this page the day after the keynote, on that reporting.
So the question — “I don’t like Siri, can I just use ChatGPT?” — has a real answer now: partly. You can hand Siri’s questions to ChatGPT. You can’t swap Siri out.
What Extensions actually is
Since iOS 18.2 back in 2024, ChatGPT has been built into Siri and Apple Intelligence: you’d ask Siri something hard, and it could suggest asking ChatGPT.
That’s still true in iOS 27. Siri’s settings have an Extensions section, and ChatGPT is the only extension in it. Claude can answer through Siri another way: the Claude app’s “Ask Claude” intent, which you can call from Siri on iOS 18 and later. Google’s help describes Gemini on iPhone only as the Gemini app, with no Siri connection. The “any model” part of iOS 27 is for developers: Apple’s Foundation Models framework lets an app call cloud models like Claude and Gemini inside that app. It isn’t a Siri setting. (Apple says Siri AI itself runs on Apple Foundation Models custom-built in collaboration with Google and its Gemini models, but that doesn’t make Gemini an assistant you can pick.)
How to turn on the ChatGPT extension in iOS 27
Three moves, from Apple’s iPhone User Guide for iOS 27 and OpenAI’s setup guide.
- Turn it on. Go to Settings → Siri (on iOS 26: Apple Intelligence & Siri), tap ChatGPT, then Set Up. If you’ve switched to Siri AI (Beta), tap Set Up Extensions, then ChatGPT, then turn on Use Extension. Apple’s steps don’t ask you to install the ChatGPT app.
- Sign in, or don’t. OpenAI says the extension works without a ChatGPT account, or with a free or paid one. Signing in saves your requests to your ChatGPT history and gives you the capabilities of your plan.
- Ask for it by name. Say something like “Hey Siri, ask ChatGPT to compose a haiku about dragons.” With Siri AI, your iPhone asks you to confirm before a request goes to ChatGPT, and you can’t turn that confirmation off. ChatGPT also shows up under Compose in Writing Tools and as a style in Image Playground.
A quick honesty flag on the first version of this page: before launch, reports described setting a third-party AI service as the default for Apple Intelligence features, and a separate voice for answers from other AIs. Apple didn’t announce either, and its iOS 27 guide documents neither.
Which one should you actually pick?
Short version, because this deserves its own page (and has one): each model has a personality. Gemini leans research and Google-ecosystem stuff. Claude is the careful writer and explainer. ChatGPT is the do-everything generalist most people already know. On an iPhone with iOS 27 the choice works differently than the rumors said: ChatGPT is the one Siri extension, Claude answers through “Ask Claude”, and Gemini stays in its own app.
If you want the full “who’s good at what” breakdown, we wrote it here: Claude, Gemini, or ChatGPT: Choose Your iOS 27 Siri. This page is the how; that one is the which.
What this means for you
If you’re a die-hard ChatGPT user. Turn on the ChatGPT extension and Siri can pass your questions to ChatGPT without you opening the app. With Siri AI, you ask for it by name.
If you live in the EU. Apple says Siri AI won’t be available initially in the EU on iPhone and iPad, and that the ChatGPT extension works only where ChatGPT’s app and service are available.
If you’ve never used Claude or Gemini. No rush. Siri AI is new in iOS 27 and, as of November 2026, a beta, and Claude and Gemini are a tap away in their own apps if it annoys you.
If you find all of this overwhelming. Totally fair. You don’t have to set anything up, and you can turn the ChatGPT extension on or off in Siri settings whenever you like.
The honest catch
- Claude and Gemini aren’t Siri extensions. iOS 27 is out, and Apple’s guide lists only ChatGPT. Claude answers through “Ask Claude”; Gemini through its own app.
- Siri stays Siri. No setting sends everything to another AI by default; with Siri AI, you ask for ChatGPT by name.
- You still need a recent iPhone. Apple Intelligence on iOS 27 needs an iPhone 15 Pro or 15 Pro Max, an iPhone 16 model or later, iPhone Air or iPhone Duo.
- Free tiers have limits. Turning on ChatGPT doesn’t unlock paid features: you get the capabilities of your plan. “Ask Claude” messages count toward your Claude usage limit, and Apple puts daily usage limits on some Apple Intelligence features that run on its servers, Siri AI among them.
The bottom line
iOS 27 doesn’t swap Siri’s brain. It hands a question to ChatGPT when you ask for it, Claude answers through its “Ask Claude” intent, and Gemini stays in its own app. The pick-any-AI setting from the spring rumors didn’t ship with iOS 27.
The bigger point: the model matters less than knowing how to use it. A great assistant with lazy prompts still gives lazy answers. If you want to get genuinely good at talking to any of these — Siri, ChatGPT, Claude, Gemini — start with our ChatGPT vs Claude course to learn what each one is actually best at. First two lessons are free with a free account.
Sources
- Turn on ChatGPT on iPhone — Apple iPhone User Guide (iOS 27)
- Use Siri to get answers from ChatGPT on iPhone — Apple iPhone User Guide
- Get started with the next generation of Apple Intelligence — Apple Support
- Major updates for Apple’s software platforms are now available — Apple Newsroom (September 14, 2026)
- Setting up ChatGPT with Apple Intelligence — OpenAI Help Center
- Use Claude app intents, shortcuts, and widgets on iOS — Claude Help Center
- Get started with the Gemini mobile app (iPhone & iPad) — Gemini Apps Help
- WWDC26 iOS guide (Foundation Models framework) — Apple Developer
- Pre-launch reports this page first relied on: iOS 27 Will Let You Pick Claude or Gemini Instead of ChatGPT for Apple Intelligence — MacRumors (May 5, 2026), Beyond ChatGPT: iOS 27 ‘Extensions’ will reportedly allow Siri to use Google Gemini and Claude — Tom’s Guide
