iPhone Handoff is one of the more unusual additions to iOS 27, allowing the same phone number to be used across two iPhones without repeatedly transferring an eSIM between them.
Apple has now published detailed support information explaining exactly how the feature works, what moves between devices, what happens with Apple Watch and Wallet, and some important limitations users should know before setting it up.
At its simplest, iPhone Handoff lets you keep a main iPhone and a secondary iPhone sharing the same number. Unlocking whichever iPhone you want to use makes that device active, while the other becomes inactive on the cellular network.
What moves between your iPhones?
When you switch devices, calls, voicemail, iMessage, RCS and SMS/MMS messages follow the active iPhone. Your Find My location also moves to the iPhone you are currently using.
Data stored in iCloud continues to sync normally between the two devices. Third-party apps can work across both iPhones too, although their behavior depends on the individual app. Some apps may sign you out when another device signs in, while banking apps may require additional authentication.
Only one iPhone can have the shared phone number active at any one time. After switching, iOS displays a “Switched to this iPhone” message to confirm which device is currently active.
What you need to use iPhone Handoff
Both iPhones need to be running iOS 27 or later, connected to Wi-Fi during setup and signed into the same Apple Account. Messages in iCloud must be enabled, and both devices need to be signed into FaceTime and iMessage using the same Apple Account.
You also need an eSIM from a carrier supporting iPhone Handoff. Carrier availability is currently limited, and carrier charges can apply.
The Apple Post previously reported that T-Mobile will charge $5 per month for iPhone Handoff in the United States. Apple lists T-Mobile as the supported U.S. carrier and Telekom as the supported carrier in Germany.
Main and secondary iPhones
During setup, one device is designated as the main iPhone and the other becomes the secondary iPhone. Apple recommends making the phone you use most frequently your main device.
Some carrier functions remain tied to the main iPhone even when the secondary device is active. Apple says this can include Call Forwarding, Caller ID and carrier account management.
If you enable iPhone Handoff while setting up a new iPhone, the new device becomes the main iPhone by default and the existing device becomes the secondary iPhone. The arrangement can also be configured later through Settings > Cellular.
What happens to Apple Watch?
Apple Watch does not automatically follow whichever iPhone is active through Handoff. It remains paired with its existing iPhone, so Apple recommends pairing your watch with whichever iPhone you use most often.
If the paired iPhone is unavailable, Apple Watch can continue using Wi-Fi or cellular where available. Without either connection, some calls, messages, notifications, health and fitness features, Siri AI and other experiences relayed through the paired iPhone may not be available.
What happens to Apple Wallet?
Payment cards can be added during setup and used on both iPhones. Car keys can also be added and shared between the devices.
There are exceptions. Apple says some Wallet items, including certain transit passes, IDs and corporate badges, may only work on one iPhone at a time.
Does iPhone Handoff work with Dual SIM?
Yes, but both eSIMs must come from carriers that support iPhone Handoff. Each number needs to be configured for Handoff separately.
Once both have been set up, Apple says the two eSIMs switch simultaneously when you unlock the other iPhone.
How do you set up iPhone Handoff?
On the second iPhone, open Settings and select Cellular, followed by Set Up Cellular or Add eSIM. Choose “Use Number on This iPhone and Another,” tap Continue and follow the instructions shown across both devices.
During the process, you can choose whether your existing iPhone remains the main device or whether the eSIM moves to the new iPhone and makes it the main device.
Apple also offers iPhone Handoff as an option while setting up a new iPhone, allowing the feature to be configured as part of the initial cellular setup.
What happens if you replace one of the iPhones?
If either Handoff device is replaced, the eSIM needs to be transferred to the replacement iPhone. The eSIM is then deactivated on the device it was transferred from.
Depending on carrier support, users may need to enroll in iPhone Handoff again after replacing a device.
How do you turn iPhone Handoff off?
This is one of the more important limitations to know. Apple says customers must contact their carrier to disable iPhone Handoff.
Deleting the eSIM from an iPhone does not necessarily cancel the service, and Apple warns that a carrier may continue charging for Handoff until the customer asks for it to be turned off.
iPhone Handoff is available with iOS 27 on supported carriers. Apple’s support document contains the latest carrier and setup information.