Fastest Mobile Network Rankings Shaken Up by Unlimited Plans

Let the debate about mobile data speeds rage on. A week after testing firm Rootmetrics crowned Verizon as the fastest network, and dismissed concerns about the impact of new unlimited data plans, a different testing firm has come to completely different conclusions.

OpenSignal, which measures mobile data speeds via an app test used by thousands of ordinary consumers, says T-Mobile has the best network overall. Nationally, T-Mobile customers who used the app speed test had the fastest average download speed at more than 16 megabits per second, followed by Verizon at 13 Mbps, AT&T at 11 Mbps, and Sprint at 8 Mbps. And perhaps even more surprisingly, T-Mobile also led the measure of availability of 4G LTE signal at 91% of all tests. Verizon was second at 90%, followed by AT&T at 83% and Sprint at 82%.

The crowd-sourced rankings from OpenSignal reflect the real world experiences of customers, unlike the more carefully planned and scheduled tests done by other firms. But that also mean that the app-based tests may not be representative of the average customer at each carrier, either.

OpenSignal also said that the new unlimited data plans were in fact slowing down the networks of Verizon and AT&T, contrary to the conclusion of Rootmetrics, which rigorously measures speeds via a fleet of professional testers in 125 major metropolitan areas.

“In February, Verizon and AT&T reintroduced unlimited data options, and we saw an immediate impact in our metrics,” OpenSignal wrote in a blog post on Wednesday. “Since March, average 4G and overall speeds for both operators began dropping in our test results.”

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AT&T (t) disputes the findings, however. “We constantly monitor our network performance,” a spokesman said. “The launch of our unlimited data plans has not impacted wireless speeds on our network.”

Verizon (vz) touted the Rootmetrics tests as a better measure of what its customers will actually experience. “If you look across all of the network tests, including the drive test results from RootMetrics—which is the most scientific available—Verizon continues to have an overwhelming lead over the competition in network performance for all aspects of a customer’s experience—coverage, reliability, and speed,” the carrier said in a statement. “Individual peak speeds from crowd-sourced tests, which OpenSignal does, don’t tell the whole story.”

The carrier also pointed to a recent survey by PC Magazine where it came out on top.

Not surprisingly given the results, several T-Mobile (tmus) executives took to Twitter to highlight the OpenSignal report. “Who can handle #unlimited? Not the other guys. More reasons @TMobile has the best unlimited network! #ReadEmAndSweep,” CEO John Legere wrote.

Sprint (s) noted that the report showed its average speed had improved. “We’ve been offering unlimited data for nearly 10 years and we have a long history managing customer demand which is why you see our scores improving while Verizon and AT&T have slowed,” the company said in a statement. “Sprint also has far more spectrum capacity than any other U.S. carrier. We find value in all of the various tests and they show similar results – that Sprint’s network is performing at best-ever levels and continues to improve.”

The debate comes at a lull in the fierce competition for wireless subscribers over the past year. In just reported second-quarter results, most carriers saw diminished switching activity and stronger profits. But that doesn’t mean the era of price cutting and free phones is over. Analysts expect competition to heat up again in the fall, when Apple (aapl) introduces new iPhones and more consumers will be considering switching carriers.

OpenSignal said the conclusions in its latest report were derived from over 5 billion speed test measurements on more than 172,000 mobile devices from March 31 through June 29.

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