Verizon customers who want one phone number to work on two iPhones are about to pay for it. The carrier will charge $10 a month for iPhone Handoff, a feature of the new iOS 27 software.

The feature lets a single phone number work across two compatible iPhones. Coverage points to the new iPhone Duo and iPhone 18 Pro as examples of devices that qualify. There is a catch: only one iPhone can use the number at a time.

The price is the headline for many people. Verizon's $10 monthly charge is double the $5 that T-Mobile charges for a similar setup. For anyone choosing between carriers, that gap adds up to $60 a year.

Carrier fees for add-on features have a long history of drawing attention. In January 2010, the FCC sent letters about early termination fees to AT&T, Sprint Nextel, T-Mobile, Verizon Wireless and Google. It was the first action of the agency's newly formed Consumer Task Force, and it followed FCC criticism of Verizon's $350 early termination fee for advanced devices.

The pricing debate has continued in the years since. In 2009, Verizon executives publicly said usage-based pricing was coming with the company's 4G network. A columnist at the time predicted Verizon would keep its unlimited plans but price them high. Those earlier discussions were about data and contracts, not number-sharing, but they show how closely customers and regulators watch carrier charges.