Touch ID is built into the side button on iPhone Duo. There is no Face ID on this model, and Apple’s iPhone compare page shows Touch ID in the phone’s secure authentication row.
The side button sits on the frame, so one sensor serves both displays. The rest of the foldable is in our iPhone Duo hub.
The short version
- Touch ID is built into the side button, and Apple says it authenticates iPhone Duo the same way whether the phone is open or closed.
- Apple says users can also unlock iPhone Duo using their Apple Watch.
- Face ID is not on iPhone Duo. Apple’s compare page gives it to iPhone 18 Pro Max.
Where the sensor is and why it is there
Apple’s iPhone Duo tech specs list Touch ID as a “Fingerprint sensor built into the side button.” The same page counts it among the phone’s sensors, alongside the barometer, the high dynamic range gyro, the high-g accelerometer, the proximity sensor, and four ambient light sensors. That list names one fingerprint sensor, and its position does not change when the Duo folds open.
Unlock switcher: see how iPhone Duo authenticates closed, open and with an Apple Watch on your wrist.
Apple’s list of external buttons and connectors names three buttons: volume up/down, Camera Control, and the side button. The same list covers the USB-C connector, the built-in stereo speakers, and the built-in microphones.
Apple describes Touch ID as integrated into the side button “for easy, secure, and consistent authentication whether iPhone Duo is open or closed.” Apple lists no authentication hardware on either display. Behind the inner screen sits an under-display FaceTime camera that Apple says stays hidden when it is not in use, and iPhone 18 Pro Max has no such camera on Apple’s compare page.
Open, closed, or on your wrist
Apple says content reacts as iPhone Duo folds, reorients when the phone is turned to the side, and switches to the appropriate display when it is flipped over. The Dynamic Island is redesigned to fit vertically on the side of the outer and inner displays, where it expands to show Live Activities and alerts.
Unlock method for every phone state
| State | How you unlock |
|---|---|
| Closed, using the 5.4-inch outer display | Touch ID in the side button |
| Open, using the 7.6-inch inner display | Touch ID in the side button |
| Wearing a paired Apple Watch | Apple Watch unlock |
Camera Control is on the same frame, and Apple says it is there “to quickly launch the camera, including the brand-new Siri Camera mode, which lets Siri see what the user sees to answer questions and take action.” Its controls cover Exposure, Depth, Zoom, Cameras, Styles, and Tone.
What you lose without Face ID, and what you keep
iPhone 18 Pro Max gets Face ID, which Apple describes as “enabled by TrueDepth technology in the Center Stage front camera.” Apple gives iPhone Duo Touch ID in the same row. What changes between the two phones is the method, not whether there is one.
Comparison table: Touch ID on iPhone Duo against Face ID on iPhone 18 Pro Max.
Apple’s compare page gives iPhone Duo four ambient light sensors where iPhone 18 Pro Max has dual, and it lists a LiDAR Scanner for the 18 Pro Max and nothing for the Duo.
The operating system underneath is iOS 27, which Apple describes as “the world’s most personal and secure mobile operating system.” Apple says iPhone Duo will be available with iOS 27.1.
FAQs
Does iPhone Duo have Face ID?
No. Apple names TrueDepth technology only in iPhone 18 Pro Max‘s secure authentication row, and it lists a 12MP Center Stage front camera for iPhone Duo against 18 Pro Max’s 18MP.
Is Touch ID on the inner side or the outer side?
Neither. The sensor is in the side button on the frame, so it is the same press in either position. iOS 27 also moves the Lock Screen controls, the Dock, and app navigation to the side of the display on iPhone Duo, which Apple says maximizes vertical space for content.
Can I unlock iPhone Duo with an Apple Watch?
Yes. Apple does not name which Apple Watch models qualify, or what setup that route needs.
Does iPhone Duo have an Action button?
No. Apple’s compare page lists an Action button for iPhone 18 Pro Max and leaves that row empty for iPhone Duo.
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