SpaceX and T-Mobile US entered a technology partnership to integrate a slice of the carrier’s spectrum into Starlink satellites. 

The alliance will enable connectivity in the 500,000 square miles uncovered by any cellular network in the U.S. currently, T-Mobile CEO and President Mike Sievert said at an event announcing the alliance. 

Sievert said the technology will enter beta as soon as late next year to facilitate messaging and messaging apps in areas out of reach from cellular towers. He added the goal is to eventually facilitate data and voice transmission. 

SpaceX Chief Engineer Elon Musk said the technology will rely on powerful antennas, calling them the “most advanced phased array antennas in the world,” in addition to other software and hardware upgrades to Starlink satellites. Musk said he’s confident that connectivity “will be able to work if [a cellphone is] in your pocket or if you're in your car,” and “certainly when you're walking outside.”

He added the satellites will be able to transmit directly to users' phones without any hardware modifications to the phones.  

Sievert said the announcement is “a call to carriers worldwide,” offering reciprocal roaming so that customers using foreign carriers will have access to connectivity in the U.S once the technology is up and running. “Our mutual view is the more companies around the world we can get signed up for this, the way T-Mobile is signing up for it tonight, the better,” he added.  

The partnership echoes an industrywide agenda to use satellite technology to enhance cellular connectivity, especially in remote areas.

Microsoft recently made moves to bolster its Azure Space program and help with technical and scaling support for customers deploying private LTE and 5G networks in remote and edge locations. And Verizon last year announced plans to pair its terrestrial mobile network with Amazon’s low Earth orbit (LEO) satellite network to push connectivity to unserved and underserved communities.