@Mark Ollig
Cellular networks have relied on ground-based cell towers, but SpaceX’s Starlink Direct to Cell now brings this model to space.
Cellular networks have relied on ground-based cell towers, but SpaceX’s Starlink Direct to Cell now brings this model to space.
This service works with regular smartphones, not just satellite phones.
Future versions are expected to move beyond Long Term Evolution (LTE) as the Third Generation Partnership Project (3GPP) advances non-terrestrial network standards.
This international standards body is developing specifications for 5G and eventually future 6G concepts.
Today’s model supports text messaging and limited data through certain apps, with broader capabilities planned as the network evolves.
Our smartphones already rely on the Global Positioning System (GPS) for navigation signals from satellites orbiting about 12,550 miles above Earth.
However, GPS is a one-way system, and smartphones do not transmit anything back to those satellites.
Alongside SpaceX, companies like AST SpaceMobile and Lynk Global are working on satellite systems that connect directly to regular smartphones.
AST SpaceMobile claims its BlueBird satellites can provide broadband directly to regular phones, while Lynk offers a similar satellite-to-standard-mobile-phone service.
Major American companies like SpaceX and AT&T are also driving advances in satellite connectivity and telecommunications services for consumers.
Mobile carriers worldwide are exploring similar partnerships.
Orange is partnering with AST SpaceMobile in Europe and Africa, while Deutsche Telekom collaborates with Starlink in Europe.
These moves suggest that “cell towers in space” could soon become a normal layer of the global wireless network.
By adding satellites to the Radio Access Network (RAN), carriers can bring mobile coverage to remote areas using non-terrestrial networks.
Compatible smartphones can stay connected even when far from regular cell towers because the signal comes from space.
Satellite cellular lets users text, call, and access data, though some functions remain limited or are still being deployed by providers.
Besides smartphones, these systems can connect vehicles, farm equipment, security sensors, and other remote devices.
When a Starlink satellite receives data from a smartphone, it sends the signal back to Earth through a ground gateway station connected to the telecommunications network.
The satellite uses a high-capacity radio link to reach the gateway.
From there, the data travels through land-based fiber networks or through a carrier’s core network, depending on the service path.
Starlink works with carriers like T-Mobile to bring mobile service to areas where regular cell towers cannot reach.
When a smartphone connects through the satellite system, it still uses the carrier’s licensed cellular spectrum.
The satellite functions as part of the radio access network while the carrier’s terrestrial network handles authentication, mobility management, emergency communications, and billing.
Many people assume a satellite-to-phone system simply passes signals between a smartphone and the ground.
In reality, the satellite acts much like a cellular tower in Earth orbit.
Instead of connecting to a tower along the highway, the smartphone connects to a satellite that provides the radio link.
The signal then passes through ground gateways into the carrier network and the wider internet.
From there, data moves through the carrier’s core network and major telecommunications and internet interconnection hubs, where networks exchange traffic.
The return signal follows the same path in reverse.
It travels from an internet server through fiber networks and carrier core systems to the gateway, then to the satellite, and finally back to the smartphone.
Since these satellites operate in Low Earth Orbit (LEO), signal delay, or latency, can fall into the tens of milliseconds under favorable conditions.
This is similar to many land-based broadband connections.
Future upgrades are expected to depend on larger satellites equipped with advanced antennas that steer radio beams toward smartphones and other connected devices on Earth.
SpaceX says the next generation of Starlink satellites is intended to dramatically increase network capacity.
This could support applications such as video streaming, cloud services, and other broadband uses.
To launch these larger spacecraft, SpaceX plans to use its Starship launch system powered by the Super Heavy rocket booster to expand the Starlink network.
Today’s column features a diagram I researched and created using Microsoft software.
Images were generated by ChatGPT 5.2 using an uploaded photo of me as a reference, along with help from Google’s Gemini AI and Perplexity AI.
At TDS Telecom, I made engineering diagrams in Microsoft Visio.
But I digress.
Today’s diagram shows how a smartphone can reach the global internet through satellite and terrestrial telecommunications infrastructure.
At the top of the image, a constellation of satellites circles Earth in Low Earth orbit.
A satellite connects to a Starlink Gateway Earth Station through feeder links operating in assigned portions of the Ka-band microwave spectrum.
These links use uplink frequencies near 27.5 to 30 gigahertz and downlink frequencies near 17.8 to 20.2 gigahertz.
Equipped with large parabolic antennas, the gateway passes the signal into the terrestrial telecommunications network.
After reaching the gateway, the signal enters land-based fiber-optic networks and travels across the country and around the world through major telecommunications and internet interconnection hubs.
The diagram also shows a second communication path where a satellite connects directly with a smartphone using licensed Long Term Evolution (LTE) cellular frequencies.
In this role, the satellite functions as a space-based cellular tower.
It links the smartphone to the carrier’s packet core network, where authentication, mobility management, and routing occur before traffic reaches the broader internet.
Using columnist prerogative, I placed myself in the right foreground of the diagram, holding a smartphone to represent the network’s end user.
The image is intended to show that this satellite system will complement, rather than replace, terrestrial networks by connecting smartphones to satellites and then into global fiber and carrier infrastructure.
Details about Starlink’s satellite-to-cell service are available on the Starlink website: .
As of early this year, T-Mobile’s T-Satellite service supports texting, location sharing, text-to-911, and limited satellite data with certain apps on compatible smartphones.
Additional satellite-to-smartphone capabilities continue to roll out.
The system is designed to work with many existing LTE smartphones through software updates, although compatibility depends on the wireless carrier and smartphone model.
For more than 40 years, cellular service has relied on ground-based towers.
Before long, the cell tower our smartphone conversations and internet connections travel over will be a space-orbiting satellite passing over Minnesota.
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Illustration depicting how a smartphone connects |
