RootMetrics Report Ranks Verizon As America’s Top Wireless Carrier, Sprint Surges Past T-Mobile
The rating is for the second half of 2014. During that time, Rootmetrics traveled 288,165 miles conducting over 5.7 million tests, including ones from 6,215 indoor locations. The goal is to evaluate each of the wireless carriers' mobile network performance from a consumer's point of view. That entails data, calling, and texting performance, both indoors and outdoors, from 125 of the most populous metropolitan markets across the U.S. You can read more about the testing methodology here.
(Source: RootMetrics)

(Source: Verizon)
T-Mobile, on the other hand, was the only carrier to never score in the 90s. Instead, it scored 85.4 in Reliability Index (No. 4), 79.1 in Speed Index (No. 3), 81.9 in Data Performance (No. 3), 84.9 in Call Performance (No. 4), and 89.7 in Text Performance (No. 4).