EE has been named as the leading UK mobile operator in an independent study of mobile performance, with Vodafone named the worst.
The UK's largest mobile operator, which was first to offer customers 4G and formed from the merger of T-Mobile UK and Orange UK in 2010, came out top in every category including reliability, call quality, mobile internet, text, and network speed.
EE CTO Fotis Karonis described the challenges of the merger in an interview with CIO last year.
The study by mobile analytics firm Rootmetrics, based on 840,000 mobile tests, placed Vodafone last in all the categories except network speed. However, Vodafone said it could not "take the results of this report seriously and neither should our customers". Vodafone also claimed that some tests were "carried out in an inconsistent manner".
The six-month study, looking at roughly one sample for every hundred mobile contracts, saw Three come a close second behind EE in terms of reliability, mobile internet and text services, while O2 came second in the speed tests and call performance.
Average speeds for networks were not given because they ranged so vastly from area to area, RootMetrics said. However, the company does offer a coverage map so that customers can see which operator offers the best service in their area.
"These results give UK consumers and businesses the most accurate view of mobile performance in the UK that has ever been made available," said RootMetrics CEO and president Bill Moore. "From nation to neighbourhood, people now have access to data showing them the best network in their area."
The tests were carried out using off-the-shelf Android handsets with the RootMetrics' analytics software installed.
Market leader EE said in January that it has attracted more than two million customers to its 4G network since it was launched in October 2012.
Meanwhile, Vodafone and O2 are playing catch up, having only launched their 4G networks at the end of last August, 10 months after EE, which was able to get a head start when industry regulator Ofcom granted it permission to use its existing 2G spectrum to roll out 4G services.
Three became the final major mobile phone operator to turn on 4G when it launched its faster network last December. However, unlike the other operators, Three said it would offer 4G to existing customers at no extra cost and offer unlimited data.