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 by Mercury Communications, a subsidiary of Cable & Wireless, it was the UK's third mobile network - introducing innovative pricing like free evening and weekend calls to disrupt the market then dominated by BT Cellnet and Vodafone - and the first in the world to operate on the GSM 1800 band.

In 1999, Deutsche Telekom acquired One2One from Cable & Wireless and MediaOne for approximately £8.4 billion. That year, 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. One2One was rebranded as T-Mobile UK in 2002, aligning it with Deutsche Telekom's global T-Mobile brand. T-Mobile launched its 3G network in 2004.

In 2010, Deutsche Telekom and France Télécom merged their respective T-Mobile UK and Orange UK businesses, forming a 50:50 joint venture, Everything Everywhere Limited (a renaming of T-Mobile UK's legal entity). The joint venture allowed T-Mobile customers to utilise Orange's 2G signal, and vice versa.

In 2012, Everything Everywhere launched a consolidated network, branded as EE; the legal entity became EE Limited in 2013. EE continued to operate the T-Mobile and Orange brands until March 2015. Legacy SIM cards remained supported by EE.

The EE network is now owned by BT, who acquired the company in January 2016 for £12.5 billion.