O2 (UK) BT subsidiaries: Esat Digifone in Ireland, Viag Interkom in Germany and Telfort Mobiel in the Netherlands. The rebranding was supported by a European advertising campaign, which began on 16 April 2002, across all four countries, at a cost of £130 million. The main launch campaign ran from 18 June and was developed by Vallance Carruthers Coleman Priest, working alongside brand consultancy Lambie-Nairn, creators of the "O2" brand identity. In March 2005, mmO2 restructured its shares and the company was relisted as O2 plc. On 30 November 2005, O2 agreed to a takeover by Telefónica, a Spanish telecommunications company, for £17.7
O2 Czech Republic different lines of business: the retail operator O2 and the wholesale infrastructure provider CETIN. The separation includes commercial and managerial leadership and management of both companies, including security, IT and control systems. The company was initially known as SPT Telecom ("Státní telekomunikační podnik", state-owned telecommunications company), and used to have a monopoly for providing fixed-line services. It was reorganized and renamed Český Telecom (Czech Telecom), after the Velvet Divorce saw Czechoslovakia separate into the Czech Republic and Slovakia in 1993. Its mobile subsidiary, Eurotel, was founded in 1990 as a joint venture between SPT (51%) and the American joint-venture Atlantic