On Tuesday, RootMetrics, a renowned independent research company that collects data on the reliability of cellular networks, released its report for the first half of 2017, Daniel Kline of themotleyfool.com reports. Testers drove 276,607 miles—further than the distance between the Earth and the moon— to perform just under 4.7 million tests of cellular performance.

Verizon once again came out on top overall, with a score of 94.5, but competitors closed the gap. AT&T received an overall score of 92.9; Sprint came in third with a score of 87.9, followed by T-Mobile at 86.5.1.6 points separated Verizon and AT&T, the range from top to bottom was a mere 8 points.

In the latter half of 2016, Verizon received an overall score of 93.9. AT&T scored 90.5, Sprint 84.7, and T-Mobile 81.2. Verizon and AT&T were separated by 3.4 points, and the range from top to bottom was 12.7 points.

The most recent report acknowledges that AT&T, Sprint, and T-Mobile all “made significant strides” in “metro-level performance,” which “provides the strongest gauge of a network for consumers.” RootMetrics considers not just “city centers” but “residential suburbs, business districts, recreational areas, and the highways that connect them” to be “metropolitan areas.” An overwhelming majority of consumers use their phones in such areas most of the time.

Verizon earned 617 first place awards in metropolitan areas. AT&T garnered 396, T-Mobile came in third with 271, and Sprint trailed the pack with 211. Verizon garnered 41 fewer first places than it did in the second half of last year, while AT&T picked up 24 more.

AT&T and T-Mobile “made big speed and reliability improvements in metro areas,” and even Sprint saw “significantly boosted data speeds and reliability at the metro level,” RootMetrics told The Motley Fool in an email.

Though RootMetrics claims the tests are impartial, some skeptics, including T-Mobile CEO John Legere, have argued otherwise. In an email to the media in February 2016, Legere accused Rootmetrics of severely handicapping T-Mobile in the study covering the second half of 2015.

“They manipulated their testing of the T-Mobile network, choosing to turn OFF Voice over LTE, our network technology that is on every single phone we sell,” the e-mail read. “VoLTE handles roughly 50% of calls made on the T-Mobile network. That is 250 million calls per day, or over 40 BILLION T-Mobile calls that RootMetrics just CHOSE to exclude in their latest tests. So the latest (and by latest, I mean up to 7 months old) RootMetrics results are worthless.

Legere claimed the “manipulation” was deliberate, and that “other carriers,” who “pay RootMetrics millions of dollars” receive favorable treatment in the tests.

RootMetrics told The Motley Fool it turned off VoLTE for the tests in question because “in the second half of 2015,” the feature “was only available on a small number of devices,” and “was not what the majority of consumers were experiencing.

“T-Mobile did add more VoLTE technology over the course of [the] last six months of 2015,” RootMetrics conceded, “but due to our rigorous scientific approach we do not switch out testing methodology for any carrier once our testing begins in a half.”

RootMetrics included VoLTE in its next report, regarding the first half of 2016, and in all subsequent studies.

Verizon is still the clear front runner among cellular service providers: it received 47 outright first place awards in metropolitan tests. AT&T was the next closest with 12 outright first places. T-Mobile won four, Sprint just one.

Last year, though, Verizon won 55 metropolitan tests outright. AT&T came in a distant second with 4 outright wins.

So, competition in the cell phone service sector is tightening, and consumers stand to benefit.

“Verizon is the leader with AT&T the clear No. 2,” Kline writes, “but for a lot of people, T-Mobile and Sprint have improved to the point where they are reasonable options, especially since they are the cheapest of the four major carriers.