AT&T and AST SpaceMobile completed what the two companies say is the first successful handoff between a direct-to-device (D2D) satellite network and a terrestrial cellular network.

The trial took place on October 21, outside Granite Falls, Washington, with AT&T noting that the test built on previous voice calls, text messages, and video calls through AST SpaceMobile’s BlueBird satellites. The trial was carried out using standard smartphones.

AT&T and AST SpaceMobile were supported in the trials by network vendors Ericsson and Nokia to handle the call from a land-based network using both vendors' equipment, while AST SpaceMobile provided its low-Earth orbit (LEO) satellite network.

Ericsson provides AT&T with the combined radio and core technology with intelligent network automation to optimize handoffs between ground-based and satellite networks, which AT&T notes can reduce transition times from seconds to milliseconds.

Nokia provided the radio access technology and mobility software that powers AST SpaceMobile's space-based network to support the handover and service continuity.

The significance of this test was to trial how feasible it would be to move a connection between AT&T’s ground-based wireless network and AST SpaceMobile’s satellite network seamlessly. D2D is seen by mobile carriers such as AT&T as complementary to their existing terrestrial coverage and key to plugging coverage gaps in hard-to-reach parts of the U.S.

According to AT&T, the test "brings AT&T and AST SpaceMobile one step closer to commercial service."

"The successful handoff is a significant milestone, but it’s not the finish line," AT&T Network SVP Robert Walters noted. "As we progress toward real-world beta services and ultimately commercial service, we’re bringing together AT&T’s broad and dense fiber footprint, the nation’s largest terrestrial wireless network, and complementary connectivity enabled by partners such as AST SpaceMobile to create a more seamless, resilient experience."

The Federal Communications Commission (FCC) earlier this year gave AST SpaceMobile permission to operate its non-geostationary orbit (NGSO) satellite system. AT&T is one of several carriers that are active investors in AST SpaceMobile.

AST SpaceMobile previously outlined plans to launch between 45 and 60 of its latest-generation BlueBird satellites this year, though it has since readjusted that target to 45 by early 2027.