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
O2 Global Network O2 Global Network O2 Global Network (O2 International Network for Sustainable Design, stylized as O Global Network) is an international network for people interested in sustainable design. The network is made up of the O2 Global Network foundation, regional hubs, local groups, liaisons and individuals (called O2's). It has currently more than 70 country contacts. O2 ("Oxygen") was founded in 1988 in Milan by Niels Peter Flint, Thierry Kazazian, Jorgi Scheicher, Jeremy Quinn and others. O2 Groups in Denmark, Finland, France, Sweden and the United Kingdom followed. Six years later (5 July 1994), Iris de Graaf and Willem Hanhart founded