Vodafone came top in mobile internet performance during a test at a sold-out Olly Murs gig at The O2.
The mobile phone operator boasted the best reliability and fastest media download speed of 5.7Mbps, with O2 coming in second on 4.4Mbps at one of four Olly Murs gigs in May.
A total of 20,000 fans filled the tent and their usage was monitored by RootMetrics.
Meanwhile EE ranked third and Three last in the survey.
CEO and President of RootMetrics Bill Moore said: “Our testing at The O2 arena shows that during a sell-out concert, Vodafone coped with mobile internet demands the best.
“The slower network speeds recorded in comparison to our testing of the wider London area in April 2015 are not entirely unexpected, as venues present particular challenges for networks.
“This unbiased information will help to give music-lovers and other attendees a better idea of the mobile performance they should expect while at The O2 arena.”