Rakuten Mobile prepares satellite communications for ordinary smartphones: how it will differ from Starlink

Japanese operator Rakuten Mobile is preparing to launch satellite communications that will not require a separate terminal or a special satellite phone. The company plans to start commercial service provision in the fourth quarter of 2026 together with American AST SpaceMobile.

The main idea of the project is simple: when a regular mobile network disappears — for example, in mountains, on an island, or after a natural disaster — a compatible LTE smartphone should receive a signal directly from a low-Earth orbit satellite.

Rakuten wants to go beyond basic messages and make the satellite channel fast enough for voice calls, data transmission, and even video calls. This approach strengthens competition in the rapidly growing direct-to-device market, where services based on Starlink already operate in Japan.

Ordinary smartphone instead of a satellite terminal

Traditional satellite communications have long required special equipment — a separate phone, antenna, or terminal.

AST SpaceMobile is building the system differently. Its BlueBird satellites should operate on mobile operators' frequencies so that the satellite effectively acts as a very distant base station for the smartphone.

Rakuten says the service is designed for ordinary commercially available LTE smartphones without hardware modification.

This does not mean that every existing phone will automatically work on launch day. The final list of compatible models, tariffs, and exact terms of commercial service have not yet been published by Rakuten.

Video call via space already tested

The technology exists not only in presentations.

In April 2025, Rakuten Mobile and AST SpaceMobile conducted a video call in Japan between two ordinary unmodified smartphones using a low-Earth orbit BlueBird satellite.

The signal was sent from a Rakuten ground station in Fukushima Prefecture to the satellite, and then directly to a smartphone. During the test, a video link was established between Fukushima and Tokyo through a standard application.

Rakuten called the test an important step towards the commercial launch of its Rakuten Saikyo Satellite Service.

Why a satellite is needed in a country with almost complete mobile coverage

At first glance, Japan seems like a strange place for such a service: the country's population is already almost completely covered by mobile networks.

But there is an important difference between population coverage and territory coverage.

KDDI estimates population coverage by mobile communication at more than 99.9%, while territorial coverage, due to mountains, remote islands, and other difficult areas, is about 60%.

It is these remaining areas that become the main market for direct satellite-to-smartphone communication.

For an individual, this can mean the ability to send a message or access the internet where building a conventional base station makes no economic sense.

Rakuten wants to provide more than messages via satellite

The company places particular emphasis on connection speed.

Rakuten and AST state that they want to provide not only SMS via satellites, but also voice and video calls, app usage, and other data transmission.

To receive the very weak signal of a regular phone from orbit, AST SpaceMobile uses satellites with unusually large antenna arrays.

In Rakuten's presentations, the antenna area of the new-generation BlueBird Block 2 satellites is indicated at approximately 223 square meters — comparable to half a tennis court.

The large antenna helps the satellite simultaneously receive the weak signal from a small smartphone and transmit data back without a special user antenna.

But Starlink already works in Japan

Rakuten is entering a market that is far from empty.

KDDI was the first in Japan to launch au Starlink Direct back in April 2025. The service initially allowed sending messages directly via Starlink satellites, and later gained support for data transmission and additional functions.

In 2026, their own Starlink Direct services appeared also at NTT Docomo and SoftBank.

For example, Docomo launched the service in April 2026. It allows using text messages and some applications in places without regular coverage, but ordinary voice calls over the satellite channel are not yet supported.

SoftBank also provides messages and limited data transmission via Starlink, but warns that the service is not intended for video viewing or other heavy data transmission.

What Rakuten and AST SpaceMobile are betting on

Therefore, Rakuten's competitive advantage must lie not simply in the fact of connecting a phone to a satellite — competitors can already do that.

The company is betting that the satellite channel will gradually approach regular mobile broadband internet in capabilities.

If the claimed capabilities are confirmed after the commercial launch, it will not matter to users whether their smartphone is connected to a tower or a satellite — they will simply maintain connection outside the terrestrial network.

This could be the next stage of market development: satellite communications cease to be a separate product and become an additional layer of a regular mobile tariff.

For Rakuten, it is also a way to cover the weak spots of its own network

The satellite project is especially important for Rakuten.

The company entered the Japanese mobile market much later than NTT Docomo, KDDI, and SoftBank and is still actively investing in the development of its own network.

By the end of June 2026, Rakuten Mobile reached 10.75 million subscriptions. The company plans to spend about 200 billion yen on mobile infrastructure development during 2026.

But building base stations in absolutely all sparsely populated areas of the country is expensive.

Satellite coverage offers an alternative: the terrestrial network can be concentrated where there are many users and high traffic, while remote areas are supplemented by a signal from space.

Rakuten CEO Hiroshi Mikitani directly said that AST SpaceMobile could be especially useful in sparsely populated areas and at sea.

Satellite will not replace a regular mobile network

However, direct connection of smartphones to satellites does not make terrestrial towers unnecessary.

The technology still has physical limitations.

A stable connection usually requires an open view of the sky. The signal works worse inside buildings, underground, in tunnels, near dense urban development, and under other obstacles.

Moreover, one satellite serves a huge territory, so its available capacity is incomparable with a dense network of terrestrial base stations in a city center.

That is why Japanese operators position direct-to-device primarily as a supplement to 4G and 5G — for zones without coverage and backup communication in emergencies.

Earthquakes make satellite communications especially valuable for Japan

Another factor is natural disasters.

During a strong earthquake, flood, or typhoon, mobile communication can disappear not because the territory was never covered, but due to damage to power supply, fiber optic lines, or the base stations themselves.

In such situations, a satellite channel becomes an independent backup.

Rakuten directly links the project development to enhancing the resilience of national communication infrastructure.

In 2026, the company was also selected to participate in the government J-LEO program, aimed at creating Japan's own low-Earth orbit satellite infrastructure.

The market is turning into a battle of two models

Two technological camps are gradually forming in Japan.

SpaceX offers Starlink to operators KDDI, Docomo, and SoftBank, using its huge already-deployed satellite constellation.

Rakuten chose AST SpaceMobile and has exclusive rights to use its service in Japan.

For AST, the Japanese market is especially important: here the company can demonstrate that its technology can work not only in tests, but also in a full network of a major mobile operator.

For Rakuten, it is a chance to get a feature that will help distinguish it from its three larger competitors.

The main test will begin after launch

Several important unknowns remain.

Rakuten has not yet disclosed the price of the satellite service, the list of supported devices, the initial coverage area, and the actual speeds users will see.

The company also warns that the timing and scope of the launch may change due to technical and other factors.

Therefore, a successful video call proves the technology works, but it does not answer the main commercial question: how stably it will operate simultaneously for a large number of subscribers.

If the launch in the fourth quarter proceeds as planned, the Japanese market will become one of the most interesting tests of the new mobile communications model. In one country, an ordinary smartphone will be able to choose between terrestrial networks and two competing satellite ecosystems — Starlink and AST SpaceMobile — without a separate satellite terminal.