T-Mobile operated the fastest wireless network in the United States during the first half of 2017, according to fresh data from Ookla.
But the launch of unlimited-data plans is taking a toll on network speeds overall.
The nation’s third-largest carrier had a “speed score” of 23.17 during the first two quarters of the year, topping second-place Verizon (21.13), AT&T (20.05) and Sprint (15.39). Ookla’s results mirror a recent study from OpenSignal that found T-Mobile claimed the top-performing network in the nation from March 31 through June 29, beating its rivals across the board in categories including LTE download speed, LTE latency and LTE availability.
“The combination of a tightly-spaced cell site grid and a smaller subscriber base than Verizon and AT&T could be the keys to T-Mobile’s success in the U.S. market and to their ability to support the exponential growth in mobile data consumption,” according to Ookla’s report. “Leveraging 700 MHz spectrum, T-Mobile has been expanding its LTE footprint into new markets. Additionally, T-Mobile has been aggressively refarming their spectrum, previously used for legacy technologies such as GSM and WCDMA, and committing those assets to the more efficient LTE technology.”
Indeed, while T-Mobile’s network excelled in urban areas, Ookla’s data suggests it suffers in rural areas. Verizon accounted for 51.6% of all samples in Ookla’s study, while T-Mobile claimed only 11.5%.
And Ookla’s results indicate carriers’ headlong rush to offer unlimited-data plans is increasing traffic on the networks, which in turn is slowing data speeds. Average mobile download speeds in the United States increased 19% year over year, but America saw its worldwide rank in mobile web speeds slide from 42nd to 44th in the world during the last year.
Speeds have been particularly slower for customers of Verizon and AT&T, Ookla said, although it’s unclear whether those decreases are due to congestion or to carrier policies that deliberately tap the brakes on data transmissions.
“Our data shows that in the case of Verizon and AT&T, the percentage of test results with the loest-end download speeds (those under 5 Mbps) shot up compared to the period before these unlimited data plans were widely available. For comparison, both T-Mobile and Sprint are seeing the opposite effect in the same time period where fewer results are below 5 Mbps in Q2 2017 than they were in Q4 2016,” Ookla wrote.
“Are some heavy data users being deprioritized? Both Verizon and AT&T say unlimited customers may experience reduced speeds if customers exceed 2 GB in a month and the cell site is congested … Whether these carriers are deprioritizing customers or customers are flocking to slower, more budget-friendly plans, both AT&T and Verizon are seeing an increase of customers experiencing speeds less than 5 Mbps.”
Ookla's data is gleaned from consumer tests using the company's Speedtest app. Ookla said roughly 3 million devices were used to perform more than 14 million tests during the first half of the year.