Vodafone the worst mobile network for the second year running: EE, Three and O2 take gold, silver and bronze medals

Vodafone has come last for the second year running in performance tests carried out by research firm RootMetrics. The UK's four major mobile networks were tested for the speed and reliability of their voice, text, and data services in the first half of 2014.

Vodafone slammed RootMetrics' rankings last year, as EE came out on top with a score of 84.6, ahead of Three (73.5), O2 (66.5) and Vodafone on 52.4.

RootMetrics said all networks showed comparable signs of improvement this year, but Vodafone did come last again. The firm also said that mobile Internet performance is "currently a two-horse race" with EE and Three scoring 85.5 and 82.7 respectively, putting them far ahead of O2 (68.1) and Vodafone (67.0).

All networks performed strongly on calls and texts, but EE came out in top place, and further outshone its rivals on network speed, only matched by Three on reliability.

Olaf Swantee, EE's chief executive said, "Today's results, along with last week's report from Ofcom, show that EE is providing the best mobile experience to businesses and consumers across the UK."

A spokeswoman for Vodafone said in a statement, "Regular independent testing of our network shows that our customers are experiencing a significantly improving network every day due to our massive on going investment." She added that the company was spending £1 billion in 2014 on improving mobile coverage and network quality.

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The research was based on more than 920,000 tests of the four network's services conducted across the UK between January and June 2014. It rated each operator out of 100 on overall performance, call performance, mobile Internet, text, network reliability and network speed.