The ISP topped six out of eight categories covering customer satisfaction in BroadbandChoices' Broadband Customer Satisfaction Survey and was named best overall provider.
"It's impressive to see that O2 scored an average of 86 percent for very/fairly satisfied across all categories. They were streets ahead of the other ISPs who averaged 60 percent," said Michael Phillips, product director of BroadbandChoices.co.uk.
BroadbandChoices also said that less than half of the respondents were "fairly satisfied" with the customer support their ISP had provided, while 53 percent were considering changing their ISP in the next six months.
"Every time we do our survey we get inundated with customers bemoaning the after sales support they receive. This spring's survey further underlines this with customer service coming bottom across the board in terms of satisfaction," Phillips added.