Vodafone dismissed a report by RootMetrics, a mobile analytics firm, which found its network to be the least reliable by far in the UK.

In an emailed statement to Mobile World Live, Vodafone said it could not “take the results of this report seriously and neither should our customers”.

The operator alleged that the way RootMetrics carried out its testing “does not appear to follow standard industry practices or is fully impartial, while it also incorporates data some of which may well be over six months old”.

RootMetrics, as far as Vodafone is concerned, conducted some of its tests in an “inconsistent manner”.

The analytics firm, for its part, emphasised the rigour of its testing. Researchers, it said, drove more than 23,000 miles – across England, Wales, Scotland and Northern Ireland – and collected more than 840,000 samples. That’s the equivalent of one sample for every 100 mobile phone contracts in the UK.

And the results make for uncomfortable reading for Vodafone.

In each category – apart from network speed – Vodafone is last. The other categories are call, mobile internet, text and network reliability.

And even in the network speed category, Vodafone can only muster a second-from-last spot with an index score of 72.9, so just nudging 3UK (69.0) into fourth position.

It’s some way off market leader EE, buoyed by 4G, which registered an index score of 102.4 for network speed.

Vodafone fares particularly badly on network reliability, scoring a meagre 40.2. EE again comes out on top (77.7), followed by 3UK (74.2) and O2 (59.1).

Indeed, in Scotland and Wales, RootMetrics finds that Vodafone is below the minimum performance threshold for reliability.

On overall performance, which takes into account results from each category, EE is judged top dog in the UK with a “RootScore” of 84.6, followed by 3UK (73.5) and O2 (66.5). Vodafone is slumped in last place with 52.4.

EE, not surprisingly, welcomed the findings.

“Today’s results show that the EE network gives customers everywhere in the UK the best mobile experience,” said CEO Olaf Swantee. “This is down to our on-going 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.”

Matthew Howett, telecoms regulation analyst at Ovum, also welcomed RootMetrics’ research, calling it one of the first attempts in the UK to explore the performance of mobile broadband networks.

“Clearly EE scores very well and this reflects both their strategy for wanting to continue to be one-step-ahead with their network and the money they have put behind it,” said Howett. “While Vodafone doesn’t score so well in comparison, they shouldn’t be written off. They too have ambitious plans for network upgrades which are being delivered through ‘Project Spring’.”

But with some acknowledgement of Vodafone’s criticisms, Howett said “some of the early results [of Project Spring] are probably not being captured in this first ranking from RootMetrics”.

“What’s clear from this snapshot,” he added, “is that for the rest of the industry to close the gap on EE in terms of network speeds and availability, it’s not going to come without a struggle.”

Vodafone, however, demurred on the validity of RootMetrics’ study.

“Those looking for more robust research,” it said in a statement, “should be approaching more established researchers, such as Ookla, who are completely independent and use hundreds of thousands of real, unbiased customers across the country for its results.”

Ookla, last month, reported Vodafone was the second-fastest mobile provider on download speeds in the UK, registering an average 11.5Mb/s. T-Mobile (EE) was reported as slightly faster (11.8Mb/s), but the remainder were far behind. O2 registered an average of 8.0Mb/s, followed by 3UK (6.6Mb/s) and Orange UK (EE) at 5.2Mb/s.

Ookla did concede at the time, however, that there wasn’t a lot of reliable data concerning the performance of mobile broadband operators in the UK.