O2 (UK) they can do it too" in reference to Vodafone and EE, O2's biggest competitors and the UK's top three mobile-telecoms companies. 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
The O2 The O2 The O2 is a large entertainment district on the Greenwich peninsula in South East London, England, including an indoor arena, a music club, a Cineworld cinema, an exhibition space, piazzas, bars and restaurants. It was built largely within the former Millennium Dome, a large dome-shaped canopy built to house an exhibition celebrating the turn of the third millennium; consequently "The Dome" remains a name in common usage for the venue. It is sometimes referred to as The O2 Arena, but that name properly refers to a smaller indoor arena within The O2. Naming rights to the district were