You can sign up for emergency satellite texting if you have a phone compatible with T-Satellite, though there are some pretty notable exceptions. It doesn't support phones with emergency satellite texting built in, including the iPhone 14 and later, as well as the Pixel 9 and up (excluding the 9A). That means you can only use T-Mobile's 911 texting if you have an iPhone 13, Pixel 9A, a Samsung Galaxy S21 and up, or a newer Motorola phone.
The iPhone 17 is Apple's most advanced phone yet, delivering blistering speed with the new A19 chip, a ProMotion Super Retina XDR display that makes every scroll feel fluid, and a camera system designed to rival pro gear. But power is only as good as the signal behind it, and that's where most carriers hit a wall. What sets the iPhone 17 apart on T-Mobile is T-Satellite with Starlink, which gives you an extra layer of coverage where no carrier towers can reach.