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How can your phone hop from a cell tower to a satellite mid-call?

AT&T and AST SpaceMobile say they handed a phone’s connection from their ground network to a satellite in a test near Granite Falls, Washington, in October 2026. The trick: the satellite sends the same LTE signal on the carrier’s own 850 MHz band, so to the phone it is just another tower, and the network hands the call to whichever cell is stronger. The catch is distance: about 500 km up, a hundred times farther than a tower 5 km away, so ten thousand times weaker. AST’s newest satellites unfold antennas of about 223 m², nearly a tennis court, and the phone transmits at its full 0.2 W to reach them, which costs battery.

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Opens Tower-to-Satellite Lab. Change the same thing yourself.

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Transcript

Mid-call, you walk past the last cell tower. It should drop. Instead, it hops to a satellite. AT&T and AST SpaceMobile say they did it in October. The trick: the satellite pretends to be just another tower. Phones keep measuring nearby cells, and the network hands you to the strongest. Now walk the phone out of range. The tower fades, the satellite wins, the call carries on. The catch is distance: a hundred times farther than a tower, so ten thousand times weaker. So the newest satellites unfold antennas nearly the size of a tennis court, and your phone shouts at full power, which costs battery. Follow for more explainers like this.

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Learn more about phones and satellites

This model shows the handover rule and the weak satellite signal. The guide adds why a satellite can pass for a tower, why it needs a giant antenna, what it costs your battery, what AT&T and AST SpaceMobile say they tested, and where the model stops.