Unlock your second iPhone and a banner appears at the top of the screen: “Switched to this iPhone.” That’s iPhone Handoff in action. Apple’s new iOS 27 feature, rolling out September 14, lets a single phone number switch between two iPhones, activating on whichever device you unlock. T-Mobile is the only U.S. carrier supporting it at launch, and it will cost you $5 a month on top of your existing plan.
How iPhone Handoff Actually Works
The feature works by assigning one iPhone as the main device and the other as a companion, with your phone number following whichever device you unlock.
One iPhone is designated the main device, keeping the original eSIM. The second becomes a companion device, receiving a linked eSIM tied to the same number through your carrier. Unlocking either phone shifts calls, voicemail, messages, and Find My to that device. Both phones cannot be active at the same time, and cellular settings like roaming and data options are managed exclusively from the main iPhone.
Before you can set it up, you’ll need the following:
- Two iPhones running iOS 27 or later
- Both connected to Wi-Fi and signed into the same Apple Account
- Messages in iCloud enabled, with FaceTime and iMessage signed in under that account
- A supported carrier eSIM (T-Mobile in the U.S. at launch)
Setup runs through Settings, then Cellular, then Set Up Cellular or Add eSIM on the companion device. Note that this feature is distinct from Apple’s existing Handoff, which moves tasks like emails or browser tabs between devices. iPhone Handoff operates at the telephony layer, not the app layer.
“T-Mobile will charge customers $5 per month to use iPhone Handoff, an eSIM feature that allows the same phone number to be used on two separate iPhones,” according to MacRumors.
The Fee Question
T-Mobile is charging a new monthly add-on for the feature, while Deutsche Telekom in Germany folds it into an existing product tier.
T-Mobile’s $5 monthly charge applies on top of whatever plan you already carry. Verizon and EE are expected to add iPhone Handoff support later this year, but neither has confirmed pricing. Until they do, T-Mobile customers are the only U.S. users who can access the feature at all.
Deutsche Telekom bundles iPhone Handoff into its existing MultiSIM offering, which typically runs 6.95 euros per month but is included at no extra charge in higher-tier MagentaMobil plans. European customers on qualifying plans get Handoff as part of a product they are already paying for, while T-Mobile’s U.S. customers are paying a new line item for a feature Apple ships in iOS at no additional cost. T-Mobile built its brand as the “un-carrier,” spending years marketing itself as the antidote to exactly these kinds of add-on fees. That positioning becomes harder to defend when a software feature ships as a new monthly line item.
Carrier support is the actual gating factor. Updating to iOS 27 is not enough. Your carrier has to enable the companion eSIM on its network before anything works. Users in markets with limited initial support are stuck waiting regardless of their iOS version. Check your plan directly with your carrier before assuming Handoff is included.
