The Continuity feature that allows you to continue text convos and calls across devices used to require those gadgets to be on the same WiFi network. With the iOS 9 beta, though, the functionality can be used over cellular and T-Mobile is the first to flip the switch for its customers. The tool allows users to send texts and make calls from your iPad or Yosemite-equipped Mac if you don't have that iPhone handy -- so long as you also have the iOS 9 beta software installed, of course. If you aren't the adventurous type and want sit out the public beta, you can rest easy knowing that the feature will arrive for everyone when the final version of the mobile OS becomes available later this year. And yes, we'd imagine other carriers will follow suit shortly.