T-Mobile continued to gain ground on wireless rivals AT&T and Verizon in speed and latency, but couldn’t beat the latter on network availability, a new OpenSignal report found.

According to OpenSignal’s August “State of Mobile Networks: USA” report, T-Mobile took top honors in four out of six categories including 3G, 4G and overall speed and 3G latency, but failed to beat out Sprint and Verizon for first place in 4G latency and 4G availability, respectively.

T-Mobile’s dominance of all three speed categories marked a slight improvement over that in OpenSignal’s February network report when it tied Verizon for fastest 4G download speeds.

OpenSignal said T-Mobile’s average LTE download speed of 16.3 mbps just managed to edge out Verizon’s average of 15.9 mbps, while both Sprint and AT&T trailed with average speeds below 13 mbps. Both T-Mobile and Verizon’s average speeds improved from their tied average of 12 mbps demonstrated in the February report.

T-Mobile blew the competition out of the water on 3G download speeds, clocking an average of 4.6 mbps. Second place AT&T only managed an average 3G download speed of 3 mbps, while Sprint and Verizon hovered at the back of the pack with under 1 mbps.

Though both T-Mobile and AT&T lost out to Verizon on network availability, OpenSignal said T-Mobile managed to “leapfrog” AT&T in its 4G availability category. Un-carrier customers who downloaded OpenSignal’s app registered access to an LTE signal 83 percent of the time compared to 80 percent of the time for AT&T customers. Verizon customers were able to connect on LTE 86 percent of the time during the testing period, OpenSignal said, while Sprint customers could only connect to LTE around 70 percent of the time.

Sprint, however, won easily on 4G latency, with a average latency of 57 milliseconds (ms). Verizon came in second with 60.5 ms, followed by T-Mobile with 61.6 ms and AT&T with 64.7 ms.

OpenSignal said its most recent results indicate “the battle lines are shifting in the U.S. Mobile market” with T-Mobile reemerging as a “viable competitor to the country’s two mega-carriers.”

OpenSignal said its latest report is based on data collected in more than 2.8 billion test conducted via more than 120,000 mobile users in the United States in the May 1 to July 10 period.