Bellevue-headquartered T-Mobile says it has completed the world's first 5G Standalone roaming connection, a technical milestone achieved in partnership with India's Jio and technology firm Syniverse.

The carrier announced the achievement Monday, Sept. 21, saying the link allows T-Mobile customers traveling internationally to stay on a full 5G Standalone network rather than falling back to older technology. The company said 5G SA roaming delivers faster speeds, lower latency and more reliable connections than prior roaming methods.

No independent verification of the "world's first" claim was found beyond the companies' own announcement.

T-Mobile's Factoria campus at 12920 SE 38th St. serves as the company's headquarters. The carrier employs roughly 6,800 people in the Puget Sound region and operates a 5G innovation hub in Bellevue's Spring District, according to DowntownBellevue.com reporting.

Ankur Kapoor, T-Mobile's chief network officer, said the company has been building toward this point for six years. "We started this journey back in 2020, laying the groundwork for a 5G Standalone future," Kapoor said in the announcement.

The head start matters. T-Mobile launched 5G Standalone in 2020, making it the first U.S. carrier to deploy the technology, according to Light Reading.

AT&T and Verizon only announced nationwide 5G SA deployments in late 2025. Since activating network slicing in 2023, T-Mobile has used the technology to offer T-Priority service for first responders and a SuperMobile tier for business customers, according to PCMag.

The roaming connection relies on Syniverse's Security Edge Protection Proxy, or SEPP, a network function that encrypts communication between carriers during roaming. Mark Yarkosky, who leads Jio's international network partnerships, called the milestone "far more than just roaming," saying in the announcement it lays the foundation for cross-network capabilities including enterprise and AI-enabled services.

The announcement describes a technical proof of concept. T-Mobile did not state when 5G SA roaming would be available as a consumer service or name a commercial launch date.

T-Mobile is scheduled to host its third-quarter 2026 earnings call Wednesday, Oct. 28, according to a separate company announcement.