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, AST says it has signed memorandums of understanding and other agreements with such carriers as Bell Canada, Orange, Telefonica, Etisalat, and Telstra.

The firms working on satellite-routed smartphone service are starting with messages: 

• T-Mobile announced in August that it would use the second generation of SpaceX’s Starlink satellite constellation to provide basic messaging services worldwide to “the vast majority” of the phones it sells. The explosion last week that ended the first test flight of both stages of the Starship rocket, which SpaceX is counting on to launch most of these v2 Starlinks, may significantly delay those plans. 

• Apple provides an Emergency SOS messaging and location-sharing feature on the iPhone 14, using the satellite communications provider Globalstar. For now, this works only in the US, Canada and 10 European countries(Opens in a new window).   

• Iridium, the successor to the company behind one of the first commercial sat-phone services, announced a collaboration with Qualcomm in January that will build support for satellite-routed messaging into certain phones built around Qualcomm’s Snapdragon 8 Gen2 chipset. It says it has the advantage of using spectrum already licensed for mobile use worldwide. “We’ll work everywhere day one,” CEO Matt Detsch said in an interview at the Satellite 2023 conference in Washington in March. 

• Lynk(Opens in a new window) has three satellites in orbit(Opens in a new window) as part of its plans to provide messaging and emergency-broadcast services to standard phones. This Falls, Church, Va., startup touts itself as “the only company in the world to have successfully sent and received text messages to and from space via unmodified standard mobile devices.” CEO Charles Miller says Lynk has signed contracts with 30 mobile operators worldwide to date.