(Credit: T-Mobile)
There's already a lot of data showing the internet speeds for SpaceX’s Starlink service. But what about its cellular Starlink system for phones, which launches through T-Mobile next month?
Using crowdsourced data from Android phones in the US, researchers in Spain estimate that cellular Starlink download speeds can reach 4Mbps.
The team at the Universidad Politécnica de Madrid tapped data from Weplan Analytics, which collects anonymized user network measurements through third-party apps. The data, taken between October 2024 and April 2025, let the researchers conduct what appears to be the first "empirical" study of SpaceX’s cellular Starlink tech, which has been available as a free beta to T-Mobile subscribers since January.
(Credit: T-Mobile beta user Ian I)Cellular Starlink is currently restricted to satellite-based SMS messages, preventing users from conducting a traditional speed test. However, the team from Madrid found they could discern the speeds by filtering the crowdsourced data for certain Mobile Country Codes and Mobile Network Codes to identify traffic that appeared to be on the known cellular Starlink network.
The crowdsourced data also included "more than one million measurements." In addition, it covered a key metric called “Signal-to-Interference-plus-Noise Ratio,” which can measure the signal quality from the orbiting Starlink satellites.
“This estimated spectral efficiency corresponds to an estimated downlink capacity of 4 Mbps per beam (from a cellular Starlink satellite), meaning the capacity a single user who occupies the entire beam bandwidth would experience outdoor in a remote or sparsely populated area,” the team wrote in a seven-page paper.
(Credit: Universidad Politecnica de Madrid)While 4Mbps is slow compared with 4G and 5G speeds, the team says the download rate might be “sufficient to support basic connectivity in remote or underserved areas,” which is what the cellular Starlink service is designed to do.
“This gap underscores the complementary nature of DS2D (Direct Satellite-to-Device) services in its current phase, aligning with its intended role as an SCS [Supplemental Coverage from Space] solution,” the team added.
(Credit: Universidad Politecnica de Madrid)Still, the team expects cellular Starlink performance to improve “through a combination of increased radiated power, continued expansion of the satellite constellation, and greater bandwidth allocation per cell.” For example, the FCC in March granted SpaceX a key waiver to operate its cellular Starlink system beyond the normal radio limits on an aggregate basis.
So far, the team hasn’t seen SpaceX increasing the radio emissions for the cellular Starlink service based on the crowdsourced data. But the paper estimates the satellite connectivity will experience a “1.5x” in the download speed to 5.9Mbps if SpaceX utilizes the FCC waiver and raises the radio emissions.
The team also predicts SpaceX can raise the speeds further to nearly 12Mbps if it can secure access to 2GHz spectrum, which the company is currently fighting to access.
T-Mobile and SpaceX didn’t immediately respond to a request for comment. But SpaceX’s own beta tests have shown the technology can reach speeds of 17Mbps and even power video calls. The company currently has 618 cellular Starlink satellites in Earth’s orbit, up from around 460 in mid-February. The goal is to roll out support for data downloads and voice over the satellite service in the coming months.
Editor's note: The paper has revised its estimates, downgrading the estimated potential speed gains to the cellular Starlink from 24Mbps to 12Mbps if it utilizes the 2Ghz spectrum and FCC waiver on radio limits.