T-Mobile takes Wi-Fi voice and text everywhere

T-Mobile USA is making a big bet on Wi-Fi, offering unlimited voice calls and text messaging over any Wi-Fi network on every new smartphone it sells, including on networks outside the U.S.

The new offering, called Wi-Fi Un-leashed, is open to all subscribers to the carrier’s Simple Choice plans. It could vastly expand the places those customers can exchange calls and text messages.

In addition to domestic use, it will allow calls into the U.S. from any Wi-Fi network outside the country, using the subscriber’s regular T-Mobile number and no additional apps. Starting Sept. 17, Wi-Fi Un-leashed also extends to flights on U.S. airlines—minus the voice calls—with unlimited text, picture messaging and visual voicemail through a partnership with in-flight Wi-Fi provider Gogo.

Wi-Fi plays a growing role in mobile operator networks, bringing in extra capacity without sapping their expensive licensed spectrum, because Wi-Fi runs over unlicensed bands. Hotspots have been a key part of T-Mobile’s infrastructure for years, but the services unveiled on Wednesday go further than any major U.S. carrier to date. It’s the latest strategy by the nation’s fourth-largest carrier to grab market share from its larger rivals through unconventional plans.

The Wi-Fi calling feature lets users make high-definition calls over wireless LANs and keep those calls going as they switch over to T-Mobile’s LTE and 3G networks, CTO Neville Ray wrote in a blog post on Wednesday. T-Mobile introduced HD calling across its LTE network earlier this year using VoLTE (voice-over-LTE) technology.

Wi-Fi voice and text essentially extends T-Mobile’s coverage and network capacity without additional network deployments, and the company wants to help its subscribers make that possible. On Wednesday it introduced the T-Mobile Personal CellSpot, an access point that users can plug in anywhere they have a broadband connection, T-Mobile said. The Personal CellSpot will prioritize T-Mobile voice calls over other traffic going over the broadband link, Ray said. Starting Sept. 17, any Simple Choice subscriber with a Wi-Fi voice handset can get a Personal CellSpot free with a $25 deposit.

All new smartphones in T-Mobile’s stores can do Wi-Fi voice and text, T-Mobile announced Wednesday, and the carrier also plans to help subscribers get a new phone with the feature through an exclusive enrollment window in its Jump device upgrade program.