The CEO of Swiss operator Salt has launched an astonishing criticism of testing agency P3, accusing it of attacking its staff, suppliers and customers.
Andreas Schönenberger made the comments following P3's latest network quality assessments of the Austrian, German and Swiss markets.
It deemed Sunrise and Swisscom Switzerland's best performing operators, with a score of 973 each, dubbing both as "outstanding" compared to Salt's "good".
Salt trailed in third with 845 points, with the operator scoring comparatively poorly for voice, particularly in a walktest along trainlines, where it scored 75 percent. However, it also trailed rivals in voice performance in towns and cities.
Drive and walktests in cities to track Salt's data performance also saw it fall behind its competitors, scoring 89 percent and 84 percent respectively.
By contrast, Sunrise scored 97 percent across both categories, and Swisscom scored 97 and 98 percent respectively.
Across the Swiss market P3 held drivetests in 18 cities and 35 small towns. Walktests took place in seven cities.
This scoring led Schönenberger to attack the methodology of the testing process and said the findings caused "big surprise and incomprehension" at the operator. He said: "In light of the investments we have put in our network infrastructure in 2016 and 2017, this is above all, an attack to our staff who are on the ground every day, to our suppliers in Switzerland and to our customers."
He said it has increased LTE availability by 10 percent between May and November and now covers 78.8 percent of the country, according to P3 rival OpenSignal.
The operator said it had carried out 674 network rollout operations this year and covers 97 percent of Swiss citizens with LTE. Its LTE-Advanced network covers half of the country's population.
In a statement, a spokesperson for P3 said: "The methodology used has been established for more than 15 years. It is today the de-facto industry standard for measuring mobile networks. In the last 12 months, 180 networks in more than 65 countries were measured.
"At all times, every operator whose network is subject to a connect mobile network test, is transparently informed in advance about everything that takes place - so was Salt."
By contrast, Sunrise welcomed the report. CEO Olaf Swantee said: "Once again we see that the Sunrise mobile network is the number one. That's no coincidence – the company's achievements in network development during the past five years are unprecedented."
He added: "We are the first operator to offer a virtually zero defect mobile network, especially so for calls, and to introduce this well-known industry standard into the mobile communications sector."
Elsewhere, Deutsche Telekom won the best operator in Germany accolade for the seventh year in a row, with P3 highlighting its data performance.
However, with an overall score of 901, it was only 25 points ahead of Vodafone with P3 noting an improved performance and a particularly strong network along railway lines.
O2 sat considerably behind at 553, which testers put down to teething problems from its ongoing merger with E-Plus.
In Austria, Telekom Austria’s A1 scored 941 points, compared to Three in second place at 906 and T-Mobile in third at 891.
Testers noted the "very high standard" of the Austrian market, with all three operators dubbed "very good" and each improving their network performance.