Direct-to-device, or D2D, is technology that lets an ordinary smartphone connect straight to a satellite. You do not need a special satellite phone or a bulky antenna.

Today’s phones need cell towers nearby. In remote areas, mountains, or at sea, there is no signal. These are called dead zones. D2D satellites fill the gap by beaming mobile service from space directly to your handset.

It works like this. A satellite carries mobile network equipment in orbit. It uses specific radio frequencies, called spectrum, to talk to phones on the ground. Your phone connects to the satellite much like it connects to a tower, as long as the satellite is overhead and your phone supports the service.

SpaceX’s Starlink and Amazon’s Leo are building D2D networks. SpaceX has approval to launch 7,500 more satellites, taking its fleet to 15,000. It also bought 65 megahertz of spectrum from EchoStar for $19.6 billion.

Governments must clear the airwaves first. The US FCC votes on October 29 on auctioning 25 megahertz for D2D and opening 482 megahertz more for extra satellite coverage. The chair says the goal is to end mobile dead zones for good.