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
Downe Communications controlling interest in the company to Charter for approximately $9 million in 1978. The company name was changed to Charter Data Services (CDS). Downe Communications Downe Communications was a publishing company founded by Edward Downe, Jr. that produced several popular magazines and provided subscription fulfillment services from 1967 to 1978. Downe was a trained journalist who worked at newspapers before becoming a magazine editor. In 1966, Downe purchased Family Magazine, a newspaper insert similar to Parade Magazine. He founded Downe Communications the following year. The company acquired the Ladies' Home Journal and The American Home in 1968 from Curtis Publishing