T-Mobile will charge customers $5 per month to use iPhone Handoff, a new eSIM-based feature in iOS 27 that allows the same phone number to be shared between two compatible iPhones.
Apple is introducing a new way for iPhone users to operate two devices with a single mobile number through iPhone Handoff, a feature coming with iOS 27. While the functionality is built into Apple’s operating system, carrier support is required, meaning availability will initially be limited to selected markets.
T-Mobile has confirmed that eligible customers in the United States will pay $5 per month for the service. Deutsche Telekom customers in Germany will also be among the first users to gain access when the feature launches.
One number across two iPhones
iPhone Handoff is designed for people who regularly use two iPhones but do not want to maintain separate phone numbers. Once configured, one device acts as the primary iPhone while the second becomes a companion device sharing the same number.
The active device changes automatically when the user unlocks either iPhone. Calls, text messages, cellular data and personal hotspot functionality can work across both devices, while T-Mobile also lists services such as Scam Shield and T-Satellite among the supported features.
There is, however, an important limitation: the phone number can only be active on one iPhone at a time. The feature is therefore intended to provide seamless device switching rather than simultaneous cellular use on two iPhones.
What is required to use iPhone Handoff?
Apple requires both iPhones to run iOS 27 or later and be connected to Wi-Fi. They must also be signed in to the same Apple Account, with FaceTime, iMessage and Messages in iCloud enabled.
Users can configure iPhone Handoff when setting up a new iPhone or later through the Settings app. Once activated, switching between the primary and secondary devices is handled automatically when either phone is unlocked.
The feature also supports Dual SIM configurations, provided both eSIMs come from carriers that support iPhone Handoff. Each eSIM must be configured separately, although supported eSIMs can switch together when the user moves between the two iPhones.
Not everything moves between devices
Although Apple is positioning iPhone Handoff as a seamless experience, some services remain subject to individual device limitations.
Payment cards and car keys stored in the Wallet app can work across both iPhones. However, certain Wallet items, including transit passes, identification documents and corporate access badges, may be restricted to one device at a time.
Apple Watch is another exception. iPhone Handoff does not automatically transfer an Apple Watch connection from one iPhone to the other, meaning users with an Apple Watch may still need to manage the relationship between their devices separately.
Once activated, iPhone Handoff remains enabled until the customer contacts their carrier to deactivate the service.
What could iPhone Handoff mean for Vietnam?
The feature could be particularly interesting in Vietnam, where eSIM adoption has expanded significantly among smartphone users and major mobile operators already support eSIM services.
However, Apple’s carrier-dependent approach means Vietnamese iPhone owners will not automatically gain access when iOS 27 becomes available. Local operators would need to support the underlying functionality before customers could use a single number across two iPhones.
T-Mobile’s $5-per-month pricing also raises an important question for the Vietnamese market. If local operators introduce similar services as paid add-ons, pricing could determine whether iPhone Handoff becomes a niche convenience for users with multiple premium devices or a more mainstream feature.
The potential use cases are nevertheless clear. Professionals who carry separate work and personal iPhones, content creators who maintain multiple devices, or users who upgrade to a new iPhone while continuing to keep an older model could benefit from maintaining a single number without physically moving a SIM or managing two separate subscriptions.
For Vietnam, the biggest opportunity may therefore be less about the technology itself and more about how quickly local carriers embrace it. If the service is offered with little or no additional cost, iPhone Handoff could become a useful ecosystem feature. If it carries a significant recurring fee, adoption is more likely to remain concentrated among users who genuinely need two iPhones.
Apple is scheduled to release iOS 27 on September 14, while the new iPhone 18 Pro models are expected to become available on September 18. Whether iPhone Handoff will reach Vietnam alongside the software update will ultimately depend on support from local carriers.