EE is the number one mobile carrier in the UK, just 18 months after launch, according to independent testing by RootMetrics. 

The research firm, which aims to get the most comprehensive mobile performance studies, found EE beat other carriers handsomely in testing. EE is number one for overall network performance, network reliability, speed, mobile internet performance, call performance, and text performance. 

It certainly sounds a little favourful towards EE, but RootMetrics did its homework. It assessed all four major operators in the UK, collecting over 840,000 test samples and driving more than 23,000 miles - the equivalent of driving from Land's End to John O'Groats 27 times.

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"Today's results show that the EE network gives customers everywhere in the UK the best mobile experience," Olaf Swantee, CEO at EE, said. "This is down to our ongoing investment in introducing 4G, increasing 3G capacity and upgrading 2G, while also spending hundreds of millions on phone call quality. We encourage the most rigorous independent testing of mobile networks in the UK, and strive to set new standards in performance and reliability."

RootMetrics didn't detail how Orange, T-Mobile, O2, Three, and Vodafone performed in the testing, but its clear EE had the upper hand. In its 18 months, EE has been aggressive in rolling out the best 4G network. It not only introduced a new 4G pay-as-you-go plan - the first in the UK - in October, but its entire handset pay monthly plans have been rejigged.

EE has also teased that it is testing new 4G technology in London that allows for mobile broadband speeds of up to 300Mbps.

In the US, RootMetrics ranked Verizon with the best reliability and AT&T with best speed. Verizon came out with the best overall win, though. 

EE has invested over £1 billion in its network, and will spend a further £500 million further expanding 4G coverage to the other 25 per cent of the population that it doesn't yet cover.