T-Mobile has begun updating its 5G network to the L4S standard (Low Latency, Low Loss, Scalable), becoming the first mobile service to do so. The technology reduces latency, resulting in improved video calls and smoother cloud gaming. T-Mobile says the format is “a key step toward a smarter, programmable 5G,” describing L4S as consistently delivering “low latency, minimal packet loss and real-time responsiveness — even under heavy traffic,” marking a significant improvement in “performance-driven use cases where every millisecond matters,” including Extended Reality (XR) “and even remote driving” for driverless cars.

“Users won’t need a special phone or plan to take advantage of the benefits from L4S. ‘This is network-driven,’ T-Mobile CTO John Saw tells The Verge.”

T-Mobile is “actively expanding” the coverage deployment of L4S on its 5G Advanced network in “many cities,” the company explains, writing in a newsroom blog that “while L4S has been used in wired environments for years, no one had scaled it in wireless — until now.” The post includes a video demo of smooth L4S delivery.

Having abandoned legacy 4G LTE for a new all-5G build-out allows for flexibility in implementing mobile network innovations like L4S “and it sets the stage for more advanced capabilities” like differentiated service tiers and network slicing, T-Mobile says (the latter referring to a technology that lets mobile carriers “slice” a single physical 5G network into multiple virtual networks).

Android Authority explains that the L4S protocol “decongests networks by allowing faster movements of data packets for specific applications in real-time,” describing it as “an improvement over existing congestion-control protocols, which first analyze packets of data and then prioritize certain apps, resulting in congestion at the receiver’s end.”

T-Mobile describes recent tests with Qualcomm and Ericsson involving L4S to smart glasses over its 5G standalone network as delivering “crystal-clear visuals, ultra-smooth frame delivery and significantly reduced motion sickness and dizziness.” The tests “underscore how L4S can pave the way for mainstream XR from niche to mainstream, especially in consumer scenarios where comfort and continuity are essential,” according to T-Mobile.

In support of “buttery-smooth” gaming controls, T-Mobile points out that Nvidia has enabled L4S in GeForce NOW, while noting when it comes to video calls, “L4S helps keep your connection crisp and clear by dynamically adjusting for network congestion” in places like airports, where bandwidth gets overcrowded.

“It reduces stutters, frozen frames, and garbled audio — making real-time communication smooth and reliable,” per T-Mobile.