Direct-to-device satellites: Four ways to connect the world

For years, direct-to-device (D2D) satellite networks felt like an experiment, pushing the limits of connectivity for remote or emergency situations.

Today, D2D is emerging as a new layer of global telecommunications infrastructure, helping fill coverage gaps and boost overall social and economic resilience.

The latest Space Connect webinar hosted by the International Telecommunication Union (ITU) underscored the changing perceptions and expanding applications of D2D.

Competing D2D visions

The session highlighted four strikingly different technical approaches, with the common aim of providing seamless connectivity from space.

Globalstar follows a traditional mobile-satellite service (MSS) operator model, utilizing the L/S (1.6/2.4 gigahertz) spectrum range typically associated with satellite communications, navigation, and radar. A constellation relying on “bent-pipe architecture” means satellites act as mirror repeaters, continuously bouncing transmissions between ground stations.

“Given that the brains of our mobile satellite system are on the ground, we are able to quickly adapt to most technological innovations by simply upgrading the electronics at our ground stations,” notes Barbee Ponder, General Counsel and Vice President of Regulatory Affairs at Globalstar.

Skylo, by contrast,represents an asset-light D2D strategy, focusing on software development and building partnerships to use existing geostationary satellites. Its cloud-based platform and global roaming agreements allow rapid scalability without the costs of launching a constellation.

“We are software defined, cloud native, modular,” explained Marko Keskinen, Managing Director for Europe at Skylo Technologies. “We are working according to software block speed, not tied to hardware or hardware platforms.”

AST SpaceMobile, meanwhile, has launched massive satellites into low Earth orbit (LEO) to deliver broadband-like services directly to people’s everyday phones, regardless of proximity to terrestrial towers. The company’s custom satellites, each spanning more than 220 square metres, maximizes spectrum efficiency and allow precise shaping of signal coverage.

“We’re able to carefully create cells to respect countries’ borders,” noted Jennifer Manner, Senior Vice President of Regulatory Affairs and International Strategy at AST SpaceMobile.

SpaceX, for its part,is expanding its Starlink LEO constellation at unprecedented speed for hybrid MSS and terrestrial mobile (IMT) spectrum usage. The global network is achieving scale, spectrum depth, and service evolution through partnerships with local mobile network operators, enabling connection on ordinary, unmodified cell phones.

“Effectively, our current satellites are towers in the sky,” said Udrivolf Pica, Spectrum and Regulatory Affairs Manager at SpaceX. “We leverage the existing gateway infrastructure – or as they like to call them in ITU, feeder links, that are being deployed around the world at a rapid pace – to support both our broadband and direct-to-cell service.”

Besides these US-based firms, other D2D providers are emerging globally, as mobile operators and regulators prepare for direct satellite links to handsets.

When spectrum boundaries blur

All these approaches embed satellites more deeply into the mobile ecosystem. But D2D spans previously distinct regulatory categories.

“We are really blurring spectrum allocation lines,” said session moderator Patricia Cooper.

The regulatory dimension is central as countries and providers consider their evolving spectrum needs ahead of ITU’s next World Radiocommunication Conference (WRC-27), where governments from around the world will agree on spectrum policies for the next four years.  

Globalstar, according to Ponder, “worked for decades on the licensing” for its L- and S-band usage.

Starlink, Pica said, aims for a share of both terrestrial and non-terrestrial radio frequencies to “ensure that everyone has access regardless of the device.”

From emergency to everyday

While D2D could soon be mainstream, it first proved its worth in crisis situations.

Providers take pride in their emergency telecommunications track record, with their services facilitating thousands of life-saving rescues and restoring signals for tens of thousands of devices at a time.

But the industry now sees a broader opportunity to close persistent mobile coverage gaps.

“Unless everyone has broadband in their phone, you’re never going to really solve the digital divide,” said Manner.

Still, a patchwork of national restrictions could hinder investments in big constellations.

Regulatory buy-in needed

Device-level regulations often present a bottleneck for D2D rollout.

Keskinen noted that Skylo’s devices already comply with 3rd Generation Partnership Project (3GPP) standards for non-terrestrial networks (NTN).

“If devices are already 3GPP NTN compliant and use a standard chipset, they should be treated as standard consumer devices,” he argued.

The technology is advancing in real time.

“This is now turning into a high-stakes global infrastructure and services market,” said Cooper.

As regulators consider spectrum, licensing and market access, their decisions will help shape how quickly D2D becomes an integrated layer of global connectivity.

Future episodes

Monthly Space Connect webinars – hosted at ITU headquarters for participants worldwide – will keep exploring critical issues and new opportunities arising from space-enabled digital services.

Don’t miss the next episode: Direct-to-Device: Paving the way for satellite 5G/6G.

Other upcoming topics include Earth observation, machine-to-machine (M2M) and cislunar (Earth-Moon) communications, and digital infrastructure resilience.

Tell us your top three areas of interest for future Space Connect sessions.

Learn more about the ITU Radiocommunication Sector (ITU-R) and its Space Services Department.

Header image credit: ITU