AT&T Completes First Satellite Call Handoff With AST SpaceMobile

AT&T has completed the first call handoff between its cellular network and AST SpaceMobile's satellite constellation, a technical step neither Starlink's current direct-to-device service nor any other rival offering can yet perform. The operator called the test a "milestone" toward "seamless" connectivity and said a beta phase will precede commercial launch, though it gave no new timeframe.

Rakuten Mobile, AST SpaceMobile's Japanese partner, is targeting a commercial D2D launch "in the near future." Both operators are moving closer to commercial service. Neither has committed to a launch date.

What did the handoff actually prove?

The test combined AT&T's terrestrial network with AST SpaceMobile's satellites in a live call transfer. Ericsson supplied the radio and core technology on AT&T's side, with automation to speed the handover. Nokia provided the radio access technology and mobility software on the satellite side.

Brian Walsh, principal product development engineering at AT&T, explained the difficulty in plain terms. Typical handoffs between cell towers resemble a driver switching lanes on a highway, he said. Handing over to a satellite is "like going from the highway to a moving plane … and that's what's so challenging about it."

The distinction matters commercially. On existing Starlink D2D service, a call drops when the user leaves cellular coverage. A fresh satellite connection must then be established. AST SpaceMobile's architecture keeps the call alive through the transition, which is what operators need for genuine continuous broadband beyond terrestrial coverage.

AT&T positions satellite as complementary to its existing fiber and wireless footprint, extending connectivity without dropped calls. In January the carrier said it would start a beta service in the first half of this year.

What is Rakuten's position?

Rakuten Mobile has worked with AST SpaceMobile since 2020 to integrate satellites with its mobile network. Hyungmin Ha, vice director for advanced technology engineering at Rakuten, told the Mobile Network Innovation Summit on non-terrestrial networks this week that the arrangement goes beyond procurement.

"It is a strategic partnership based on shared investment and common vision," Ha said.

The initial service will be constrained. Rakuten currently gets only four to six minutes of satellite connectivity as each satellite passes overhead, Ha explained, which rules out testing a continuous video call. "We don't have many satellites right now," he said.

Rakuten is also exploring deeper network integration for future services and for 6G. Ha framed integration, not the satellite link itself, as the central engineering problem: "The real challenge [with NTN] is integration. … The true quality of our service isn't just in the satellite or the ground network; it lies in the seamless integration between the two. If that connection fails, the service doesn't just slow down; it just disappears. This is why integration is not just a technical detail. It is the deciding factors between operational excellence and chaos."

Who is ahead in the D2D race?

AST SpaceMobile has slipped against its own launch schedule. It expects 45 satellites in orbit in early 2027, the number it says is needed for continuous US coverage. It has 13 today, roughly 29 percent of that target.

The gap leaves room for competitors. SpaceX plans to start launching next-generation D2D satellites next year, with NTN network integration built in and commercial services slated for early 2028. Amazon's Leo constellation is also in the race.

The strategic divergence is sharp. SpaceX intends to compete directly with US carriers through a Starlink hybrid satellite-terrestrial network. AST SpaceMobile is taking the opposite path, integrating with telco partners such as AT&T, Verizon and Rakuten to extend mobile broadband into coverage "not-spots." For operators, the partner model preserves the customer relationship; the SpaceX model does not.

For now, AT&T's handoff gives the partner camp its first end-to-end proof. Whether it converts into commercial advantage depends on launch cadence: AST SpaceMobile must roughly triple its constellation before continuous service becomes possible, while its rivals' timelines point to services arriving within two to three years.