AST SpaceMobile has successfully carried out a direct voice call between the US and Japan, via its LEO satellite constellation, using standard smartphones.

It’s the standard smartphones bit that makes this story noteworthy. AST SpaceMobile says it’s a world first; that is, it’s the first time anyone has made a direct voice connection from space to unmodified cellular devices.

The company worked with some of its big name mobile operator partners to achieve the feat. The first call was made late last week from the Midland, Texas area using AT&T spectrum and a Samsung Galaxy S22 smartphone, to Rakuten in Japan, the companies announced on Wednesday. Oh, and Vodafone was also there.

AST SpaceMobile says the test calls – presumably it made more than one – validate its network architecture and systems, including its BW3 satellite, which it describes as the largest commercial communications array in low-earth orbit, and paves the way for space-based cellular broadband. The company’s target market is the close to 50% of the world’s population that has no mobile broadband coverage.

“Achieving what many once considered impossible, we have reached the most significant milestone to date in our quest to deliver global cellular broadband from space,” said AST SpaceMobile chief executive Abel Avellan, who it seems participated in that first test call.

Indeed, Rakuten chairman and CEO Mickey Mikitani congratulated AST SpaceMobile on the test call, and described it as a “thrill and honour” to have his team speak with Avellan.

Meanwhile AT&T and Vodafone – engineers from all three telcos participated in the preparation and testing of the first voice calls via BW3 – leant heavily on their heritage in the industry in their own comments on the milestone. As we probably could have predicted, Vodafone’s interim CEO Margherita Della Valle again referenced the sending of the first text message back in the early 1990s, while AT&T’s network head Chris Sambar went even further back, to “the birth of the telephone 147 years ago.” Clearly both parties will add this satellite-to-smartphone first to their industry legacies.

“This is just the start,” added Della Valle. “As a lead investor in AST SpaceMobile, we will continue to break technological boundaries by connecting many more millions of people across the planet when the service becomes commercially available.”

There was no hint in the announcement of when that might be, incidentally. And it’s worth pointing out that AST SpaceMobile’s lengthy ‘forward-looking statements’ warning includes the risk of delays in commercialisation and the cost – and even likelihood – of raising more capital. This is the satellite industry after all.

AT&T is pretty committed to the idea of space-based communications though.

“We connect people to greater possibility, and this important milestone with AST SpaceMobile is a big step and we can’t wait to see what’s next in our space-based journey,” said Sambar, having also thrown in a reference to AT&T’s participation in the Moon landings…from a comms perspective, of course.

AST SpaceMobile noted that as well as working on the test calls, its engineers carrier out initial compatibility tests on a range of smartphones and devices, which it did not list. However, it said that the phones successfully exchanged SIM and network information directly to BW3. It added that further testing and measurement on smartphone uplink and downlink signal strength confirmed the ability to support mobile broadband speed and LTE and 5G waveforms.

All in all, it appears that things are progressing in the right direction for AST SpaceMobile, from a technical point of view. It will doubtless be a similarly challenging task to make the numbers stack up for commercial services.

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