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
Concentration of media ownership Four" of American network (terrestrial) television (this despite the fact that the CW was, in fact, partially owned by one of the Big Four in CBS). In television, the vast majority of broadcast and basic cable networks, over a hundred in all, are controlled by eight corporations: 21st Century Fox (the Fox family of channels), The Walt Disney Company (which includes the ABC, ESPN and Disney brands), National Amusements (which includes CBS Corporation and Viacom), Comcast (which includes the NBC brands), AT&T (which owns WarnerMedia), Discovery Communications, E. W. Scripps Company, Cablevision (now known as Altice USA), or some combination