T-Mobile is to be the first to test its upcoming Starlink satellite direct-cell service, which promises to fill in 500,000 square miles of terrestrial cell tower dead zones in the US. The company created where people can sign up for free, and testing will begin “early next year.”

The T-Mobile Starlink beta program is open to all post-paid customers with “compatible” satellite phones, although the company hasn’t shared a complete list of which devices will work. To start, registered beta testers will only get to try out satellite texting, with voice calls and data coming later.

The FCC handed T-Mobile and satellite partner SpaceX approval last month to allow satellite-to-service for customers, although not with the higher radio emission power needed for real-time voice and video calls. In August, Verizon and AT&T raised concerns that a fully realized T-Mobile service could interfere with their competing satellite services.

T-Mobile tested direct-to-cell emergency alerts in September, and in October, SpaceX turned on satellite text messaging to T-Mobile customers in areas affected by Hurricane Helene and Milton.