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
The O2 redeveloped. The area is served by the Jubilee line's North Greenwich tube station, which was opened just before the millennium exhibition, and by bus routes. Thames Clippers operate a river boat service for London River Services; the present tenants, AEG, purchased Thames Clippers in order to provide river links between central London and The O2. As well as a commuter service, Thames Clippers operates the O2 Express service. Local buses also serve the station and the nearby O2. On 23 February 2017, O2 announced that they had agreed a deal with AEG to maintain the naming rights of The O2