O2 (UK) O2 (UK) Telefónica UK Limited (trading as O2 – stylised as O) is a telecommunications services provider in the United Kingdom, owned by the Spanish multinational Telefónica, and is headquartered in Slough. With 25 million subscribers (as of December 2017), O2 is the second-largest mobile network operator in the United Kingdom after EE, with Vodafone in third place. O2 was formed in 1985 as Cellnet, a 60:40 joint venture between BT Group and Securicor. In 1999, BT Group acquired Securicor's share of Cellnet and the company was later rebranded as BT Cellnet. In June 2000, BT Cellnet launched the world's
O2 (UK) 2017). Samsung Galaxy: S7, S7 Edge, S8, S8+, Note 8, Sony Xperia XZ Premium and OnePlus 6. Alongside mobile telephone services, the company also provided fixed line services and home broadband. O2 purchased Be Un Limited, an internet service provider in the UK, for £50 million in June 2006. O2 retained the Be brand, and launched a separate O2-branded broadband service on 15 October 2007, using the Be network. O2 announced in June 2011 a fibre optic broadband service designed to compete with the BT Infinity product, using FTTC technology. BSkyB agreed on 1 March 2013 to buy the fixed