Apple's Handoff lets two iPhones share one number, but it won't come cheap

The iPhone 18 Pro, which Apple announced last week, lacks any significant upgrade other than its new chip. Even the new camera Apple touted adds a feature Android brands have had for years. Irrespective of that, something that makes the iPhone 18 Pro truly compelling is the ability to use another iPhone with the same phone number, much like you would with an Apple Watch.

This feature is called “Handoff,” and it currently requires carrier support. That means only a handful of carriers will initially support it and may charge you more for the service, especially as they’re giving you the opportunity to sell you another line. At launch, T-Mobile is the only carrier in the US to support Handoff, while Verizon is likely to add support in the coming months.

As per initial reports, the feature wouldn’t be cheap, and the Uncarrier will charge you $5 every month to let you use the same number on another iPhone. The subscription charges have been confirmed by T-Mobile (via MacRumors) in an iPhone 18 Pro-centric blog post.

Beyond the extra monthly charges customers will pay, there are a few caveats to keep in mind. The most important of those is that only one iPhone can have the connection active at once — unlike the Apple Watch. The service will switch between the two iPhones automatically based on which phone is unlocked, and your messages and Find My will become active on that phone.

Some settings or features, such as Call Forwarding, may only be available through the primary phone, Apple says. However, both devices will support essential services, including calling, SMS, data connectivity, and mobile hotspot, as per T-Mobile. The Uncarrier also says Scam Shield and T-Satellite will be available across both iPhones on eligible plans.

To use the service, both iPhones must run iOS 27. The secondary phone must also have an eSIM that isn’t already bound to an existing number.

We don’t know how reliably the feature works beyond Apple’s tooting of its own horn, but we should be able to tell you more once we’ve tested it ourselves. That should be possible after September 18, when the new Pro iPhones hit shelves in the US.