3, (or Three) is the newest mobile phone network to start operating in the UK.In May 2000 the UK government awarded five licences to allow third generation wireless services to be run. The largest of the five was set aside for a new entrant in order to increase market competition, which was subsequently bought by Hutchison (current owners of 3).Hutchison were also the original owners of Orange, but then sold the company to Mannesmann during the telecomms boom. Vodafone then bought Mannesmann, which meant having to sell Orange yet again. Hutchison gathered even more money by selling their 10% stake of Mannesmann before the telecomms bubble burst and valuations fell considerably.
O2 was formed in 2001 following the split from British Telecom of its former mobile business, BT Cellnet. The demerger was part of BT's plan to reinforce its financial position following over-expansion in the 1990s.
The company is one of the UK's leading providers of mobile services to businesses and consumers across Britain, by the end of 2005, 27.4 million people had joined O2.
Orange UK is a mobile phone operator as well as an internet service provider in the UK, which was founded in 1994.
The company is owned by Orange SA, a subsidiary of France Telecom. They took control after a sequence of previous ownerships, (initially owned by a consortium of Hutchison and British Aerospace).
A German mobile network operator headquartered in Bonn, Germany, T-Mobile is the UK network of T-Mobile international. Previously known as One 2 One in the UK, the company was originally owned by Mercury, and then by Cable & Wireless.
T-Mobile went through a transformation and now boasts 19.2 million subscribers in Britain, which has made it the second largest mobile network in the UK. The company operates across Europe and the USA and worldwide, now has reached over 100 million customers.
Formerly known as NTL: Telewest Incorporated, Virgin Mobile is one of the UK's leading mobile virtual network operator. The UK division is a subsidiary of Virgin Media Inc.
It entered the mobile market in November 1999 and currently has more than 4 million customers.
Vodaphone was formed in 1984 as a subsidiary of Racal Electronics Plc. In 1991 it had fully split from Racal Electronics and became an independent company, and consequently changed its name to Vodafone Group Plc.
Vodafone has a notable presence across the world, which shows in its latest global customer figures – 198.6 million by the 31 December 2006, and a market value of around £86 billion (November 2006).
In the UK, the regional customer base at the end of June 2000 was more than 10.77 million.
O2 was formed in 2001 following the split from British Telecom of its former mobile business, BT Cellnet. The demerger was part of BT's plan to reinforce its financial position following over-expansion in the 1990s. 
