Verizon and AT&T recovered from an initial performance dip following the revival of unlimited plans in 2017, but still lag behind speed gains made by rivals T-Mobile US and Sprint, OpenSignal reported.

In a blog post, the network testing company said measurements covering the period from November 2016 to November 2017 show Verizon and AT&T posted their highest speed scores between December 2016 and February 2017. Following the reintroduction of unlimited plans in the latter month, OpenSignal noted both operators’ speed scores “dropped considerably” before bottoming out in August 2017.

At Verizon, speeds dropped from nearly 18Mb/s to 14.4Mb/s, while AT&T speeds dropped from just over 14Mb/s to a low of 12.1Mb/s.

While the operators have somewhat recovered, OpenSignal pointed out they have yet to attain their pre-unlimited speeds. In the meantime, the company added T-Mobile and Sprint have gained “considerable ground”. Sprint reportedly ended November 2017 with a new high speed of just under 12Mb/s, while T-Mobile eclipsed Verizon to take the top speed ranking with an average of nearly 19Mb/s.

In November 2017, Verizon’s VP of network support Mike Haberman told Mobile World Live network usage had changed following the introduction of unlimited, but insisted the shift didn’t have much of an impact.

“It was pretty seamless from our perspective. The only difference now is a slightly different usage pattern that we’re engineering for.”

OpenSignal acknowledged Verizon and AT&T now appear to have a handle on how to manage unlimited, but warned “even if both operators fully recover, they will likely find that the unlimited crisis has cost them major stakes in the 4G race”.