Mobile phone calls made in rural areas over Vodafone's network are most likely to fail, according to research by industry regulator Ofcom.

The Office of Communications looked at network performance data from EE, O2, Three, and Vodafone. 

It found that 7.4 percent of Vodafone’s calls across the UK failed, compared to just 3 percent from rival EE, which scored highest in Ofcom’s call quality rankings. 

Vodafone’s dropped call rate increased to 20.1 percent in rural areas across the UK, compared to just 6.3 percent for EE.  

“It’s great to see our ongoing investment in phone calls reflected in Ofcom’s report, confirming that we continue to provide the best call experience across the UK, particularly in rural areas,” said an EE spokesperson. “We’re investing hundreds of millions each year in expanding the reach of our network so that more people can make phone calls in more places.”

A Vodafone spokesperson said: “Regular independent testing shows we’re market leader for call set up and we’re one of the best for call continuity. Vodafone continues to invest heav­ily in its network and services, and we’re spending £1bn alone this year to improve mobile coverage and quality.”

While EE had the best overall coverage across the UK, O2 had the best coverage in the country’s major cities.

The report, Consumer experiences of mobile phone calls, is based on data provided by Rootmetrics,  a company that analyses network performance on mobile handsets.