'3' accounts for over 40% of the UK's mobile data traffic

"Over 40% of mobile data being used in the UK runs across Three’s network with nearly all of its new customers signing up to contracts with smartphones, according to the operator’s CEO David Dyson.
Speaking earlier today at the Westminster eForum, he said traffic on Three’s network, one of the few to offer unlimited data packages, doubled in the past 12 months to hit 6m GB a year, with “virtually 100%” of new customers signing up for smartphone contracts."

Source:  NMA, 27th March 2012