KDDI and T-Mobile US Strike D2D Roaming Agreement

KDDI and T-Mobile US have announced a new partnership enabling users to roam onto T-Mobile’s Starlink Direct-to-Cell (D2C/D2D) coverage area while in the United States beginning November 17, 2025. The agreement creates one of the world’s first international D2C roaming frameworks, expanding service continuity for subscribers travelling between Japan and the U.S.

“au Starlink Direct” allows standard smartphones to send messages and use supported data apps via direct satellite links wherever the sky is visible, eliminating traditional mobile coverage gaps. With roaming extended to T-Mobile’s Starlink footprint, KDDI subscribers will gain satellite connectivity across vast rural and remote areas of the U.S.

The service maintains core use cases such as location sharing, emergency messaging, and basic data transfer in areas without terrestrial coverage. It also underscores the global evolution of NTNs as mobile operators collaborate across borders to provide unified, satellite-supported mobility services.

The arrangement appears to be:

• Japan’s first international D2C satellite roaming offering, and

• The first introduction of Starlink’s D2C service via T-Mobile in the U.S., enabled for foreign roaming customers.

KDDI plans to expand coverage and service features during FY2025, further integrating satellite roaming into its mobility strategy and reinforcing D2C as a foundational layer for global travel connectivity.

SOURCE: https://newsroom.kddi.com/news/detail/kddi_nr-828_4211.html (Japanese)