Life's For Sharing. T-Mobile 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 Central and 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 Verizon Wireless, AT&T Mobility, and Sprint Nextel.