T-Mobile UK

T-Mobile (UK) Limited, trading as T-Mobile UK, was a mobile network operator in the UK. First launched as Mercury One2One (stylised one2one) on 7 September 1993, the network was originally operated by Mercury Communications. One2One was purchased by Deutsche Telekom in 1999, who rebranded it with their global T-Mobile brand name in 2002.

In 1999, One2One became the world's first network to provide wireless network infrastructure to a mobile virtual network operator (MVNO) when Virgin Mobile was launched as a joint venture between One2One and Virgin Group.

In 2010, Orange UK merged into T-Mobile UK to form a joint venture, Everything Everywhere, which continued to operate the T-Mobile and Orange brands until March 2015 and allowed T-Mobile customers to utilise Orange's 2G signal and vice versa.

In 2012, Everything Everywhere launched their new network branding as EE. T-Mobile SIM cards remained fully supported by EE, who are ultimately owned by BT since they acquired the company in January 2016 for £12.5 billion.