T-Mobile Users Can Now Use Their Phone Numbers on Other Devices

T-Mobile US Inc. is now letting customers link their phone numbers to any other internet-connected device -- tablets, laptops, or work-assigned phones -- through a new app called Digits.

With the service, T-Mobile is targeting consumers who want to use their 10-digit phone number to send and receive text messages using their computers and tablets as well. Digits will also give some of the 30 million people who carry two phones -- business and personal -- the option to use just one, according to Chief Operating Officer Mike Sievert.

Starting May 31, all T-Mobile phone numbers will be portable at no extra charge, and subscribers will have the option to add a second Digits phone number for an additional $10 a month. The Bellevue, Washington-based company is introducing the service after a five-month trial.

Today’s mobile-phone users talk and text using devices that are assigned a specific 10-digit phone number programmed into SIM (subscriber identification module) cards. As more daily communication has moved over the internet, web-based applications apart from the nation’s phone network, like Facebook’s WhatsApp, Google Voice and Microsoft’s Skype, have taken off. Now calling, video-chatting and texting within a single app are commonplace.

T-Mobile’s Digits, which has been in development for two years, is designed in part to capitalize on the popularity of those apps. “T-Mobile said ‘we can do that too,”’ said Roger Entner, an analyst at Recon Analytics LLC.

But there’s a security risk. “The moment you make your phone an app you make it potentially vulnerable to hacking,” Entner said. “You are trading a little security for convenience.”

T-Mobile’s Digits app requires two-factor authentication, meaning customers must enter a log in and password. An authorization code is sent to a device the first time Digits is activated.

The service will be enabled on all T-Mobile accounts, but customers won’t be forced to use it.

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