The outspoken T-Mobile CEO criticized Bellevue-based RootMetrics, which analyzes mobile network performance. RootMetrics’ latest rankings put Verizon Wireless on top, followed by AT&T, Sprint and T-Mobile.

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Outspoken T-Mobile US Chief Executive John Legere is on the attack again, and this time the target is another Bellevue company, RootMetrics.

The research firm released its semiannual study Thursday in which it ranks mobile network performance. As in the previous four years, Verizon Wireless topped the U.S. list for overall performance. The wireless giant swept the field this year, beating out AT&T, Sprint and T-Mobile in network reliability, network speed, and data, call and text performance.

But Legere said RootMetrics is biased against T-Mobile because the Bellevue carrier isn’t paying the research firm “like the other carriers.”

“RootMetrics should be banned as an independent source for network benchmarking, period!” Legere said in a statement sent to media before the study was released.

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The results are skewed, Legere said, because RootMetrics didn’t account for calls made over T-Mobile’s Voiceover LTE feature, which the company says handles about 50 percent of customer calls.

RootMetrics did not include Voiceover LTE calls in the study, which covered the second half of 2015, because when the study began the feature was available only on a small number of T-Mobile devices, said Julie Dey, RootMetrics vice president of marketing.

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

Voiceover LTE is being counted in the first half of 2016. Dey added that anyone can buy the company’s reports, but “there is absolutely no outside influence over our testing, analysis and results.”

Verizon issued a truth-and-myth report about its relationship with RootMetrics, stating it does not pay to produce the reports. It does pay to license RootMetrics rankings for use in Verizon advertisements.

RootMetrics echoed the claim, saying it is “completely and steadfastly independent.”

Legere is known for his outspoken comments on social media and in person, usually directed at the other three leading U.S. carriers. He sometimes calls the trio Larry, Curly and Moe, a reference to “The Three Stooges.”

Though it still ranked fourth overall in RootMetrics’ report, T-Mobile is flying high from its fourth-quarter earnings report Wednesday that showed profit had nearly tripled.

The company, now ranked as the No. 3 U.S. wireless carrier by number of customers, added 2.1 million customers during the quarter, bringing its total to 58.9 million.

T-Mobile expects to gain 3.4 million customers this year.