T-Mobile just got a reminder that having the fastest network on paper does not always mean giving customers the smoothest real-world experience. 

One new report says T-Mobile finished last in task success and reliability in vendor-based testing for the second half of 2025, even though it still led in median download speeds and 5G availability. In other words, T-Mobile kept its speed edge, but AT&T and Verizon did better when it came to everyday tasks going through without hiccups. 

As reported by PhoneArena, Ookla’s RootMetrics ran more than 3 million tests in the U.S. during the second half of 2025 and ranked T-Mobile’s Nokia and Ericsson markets fifth and sixth out of six. The same report said T-Mobile was still the only carrier to top 100Mbps median download speeds in all 125 major markets, and it posted 95.2% 5G availability versus 81% for AT&T.

That weak spot may already be part of what T-Mobile is trying to fix. In a separate report, T-Mobile and Ericsson said they tested an AI-native Scheduler with Link Adaptation on customer traffic over T-Mobile’s 5G Advanced network. The companies said the trial improved spectral efficiency by nearly 10% and raised download speeds by 15%, with a commercial rollout planned for the third quarter of the year.

Taken together, the two reports paint a simple picture for regular users: T-Mobile still has plenty of speed, but it also has room to improve consistency. If this new AI-based upgrade works the way T-Mobile and Ericsson say it will, customers could see fewer weak-signal slowdowns and a more stable experience when streaming, gaming, or just trying to load an app.

Source: PhoneArena, PhoneArena