O2 Europe Ltd. provides integrated mobile, fixed, and broadband services. The Company offers mobile telecommunications services using universal mobile telecommunications system, general packet radio services, and fixed line systems. O2 is the second-largest mobile network operator in the United Kingdom after EE, with Vodafone in third place. The company was formed in 1985 as Cellnet, at first a joint venture between BT Group and Securicor, later wholly owned by BT. Cellnet was the second mobile phone network to launch in the UK after Vodafone three years early. In 2006 the company was purchased by Telefónica, who retained the O2 brand and the company's UK headquarters.

 

O2 has filed to list on the London Stock Exchange in May of this year to expand its operation into the United States, Canada, Australia and New Zealand.