Advert: date=May 2008

T-Mobile is a group of mobile phone corporate subsidiaries (all under the ownership of Deutsche Telekom) that operate GSM and UMTS networks in Europe and the United States. The "T" stands for "Telekom." T-Mobile also has financial stakes in mobile operators in Eastern Europe. Globally, T-Mobile has 101 million subscribers, making it the world's sixth largest mobile phone service provider by subscribers and the third largest multinational after the United Kingdom's Vodafone and Spain's Telefónica. T-Mobile USA is the fourth largest wireless telecommunications network in America after AT&T, Verizon Wireless, and Sprint Nextel.

T-Mobile International has a substantial presence in eleven European countries (Austria, Croatia, Czech Republic, Germany, Hungary, Macedonia, Montenegro, the Netherlands, Poland, Slovakia, and the United Kingdom) as well as in the United States.

In recent years Deutsche Telekom attempted to acquire rival mobile network operator O2, but in 2006, Spain's Telefónica acquired O2.

In March 2008, the company announced they are to acquire Siemens Wireless Modules (now known as Cinterion Wireless Modules)as part of the JOMA consortium. The Siemens Wireless Modules spin off to Cinterion Wireless Modules was concluded on May 1, 2008.

Austria

T-Mobile in Austria is the 2nd largest carrier in the country. It recently acquired low-cost operator Tele.Ring from Western Wireless International in 2005 and still uses the Tele.Ring brand in the country for low cost offers.Fact: date=August 2008

Germany

On July 1, 1989, West Germany's state-owned postal monopoly, Deutsche Bundespost (DBP) was reorganized, with telecommunications consolidated in a new Deutsche Bundespost Telekom unit; this was renamed Deutsche Telekom in 1995, and began to be privatized in 1996.

The analog first-generation C-Netz ("C Network", marketed as C-Tel) was Germany's first true mobile phone network (the A and B networks, also owned by the post office, had been previous radiotelephone systems), and was introduced in 1985. Following German reunification in 1990, it was extended to the former East Germany.

On July 1, 1992, the Deutsche Bundespost Telekom began to operate Germany's first GSM network, along with the C-Netz, as its DeTeMobil subsidiary. The GSM 900 MHz frequency band was referred to as the "D-Netz", and Telekom named its service D1; the private consortium awarded the second license (formerly Mannesmann, now Vodafone) chose the equally imaginative name D2. In 1996, as Deutsche Telekom began to brand its subsidiaries with the T- prefix, the network was renamed T-D1 and DeTeMobil became T-Mobil; the C-Netz, in the process of being wound down, was not rebranded, and was shut down in 2000. In 2002, as Deutsche Telekom consolidated its international operations, it anglicized the T-Mobil name as T-Mobile, although sometimes also using the name T-D1 within Germany. It is still common for Germans to refer to T-Mobile and Vodafone as D1 and D2.