AT&T, AST SpaceMobile Claim First Smartphone-to-Satellite Phone Call
A few recent calls from Texas to Japan took a groundbreaking detour—to a satellite in low Earth orbit and back. The carrier and the satellite operator behind them, AT&T and AST SpaceMobile, announced(Opens in a new window) this Tuesday as “the first time anyone has ever achieved a direct voice connection from space to everyday cellular devices.”
AST is one of a handful of companies working to allow satellites to act as cell towers that happen to be a few hundred miles above Earth. Its competitors have focused on the lower-bandwidth medium of messaging.
The first such call—to the Japanese tech giant Rakuten—was placed in AST's Midland, Texas, neighborhood at 8:31 p.m. Central Time on April 20 and routed through its BlueWalker 3 satellite(Opens in a new window). It started with an unmodified Samsung Galaxy S22 phone on AT&T spectrum and also involved help with engineers from the UK telco Vodafone.
AT&T said separately that it involved its Band 5 850MHz spectrum but didn’t offer further details; as voice over 5G remains a T-Mobile exclusive, that suggests it was a 3G or LTE call. AST’s release also says that uplink and download testing during these sessions verified “the ability to support cellular broadband speeds and 4G LTE / 5G waveforms.”
The press release did not specify what was discussed on the call, although we would like to think it began with “Ahoy!,” Alexander Graham Bell’s proposed phone-call greeting(Opens in a new window).
AST launched BlueWalker 3 in September into a roughly 310-mile-high(Opens in a new window) orbit to test its system for satellite-linked voice calling, which it plans to deploy starting with the launch of five BlueBird satellites in 2024. In addition to AT&T, Rakuten Mobile, and Vodafone,
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