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
Safelayer Secure Communications Safelayer Secure Communications Safelayer Secure Communications S.A. is a Spanish private company founded in May 1999. It develops software products on the Public key infrastructure area (digital security for the identity management, electronic signature and data protection). Safelayer's technology is part of the three major certification and digital identity projects in Spain: Fábrica Nacional de Moneda y Timbre, the Spanish ID card "DNI electrónico" and the Spanish E-passport. Safelayer's technology also secures the NATO X400 messaging system". Safelayer's technology has been and Common Criteria certified. Currently, Safelayer is the only company with a whole family of products CC EAL4+ certified.