Wikipedia
T-Mobile International AG is a German holding company for Deutsche Telekom AG's various mobile communications subsidiaries outside Germany. Based in Bonn, Germany, its subsidiaries operate GSM, UMTS and LTE-based cellular networks in Europe, the United States, Puerto Rico and the U.S. Virgin Islands. The company has financial stakes in mobile operators in both Central and Eastern Europe.
The T-Mobile brand is present in 13 European countries – Austria, Croatia (as Hrvatski telekom), Czech Republic, Albania, Germany (as Telekom), Hungary, Macedonia, Montenegro, the Netherlands, Poland, Romania and Slovakia, as well as the United States, Puerto Rico, and the U.S. Virgin Islands. It was present in the United Kingdom up until 2010, when T-Mobile and Orange S.A. merged to form EE.
Globally, T-Mobile International subsidiaries have a combined total of approximately 230 million subscribers. T-Mobile International is the world's fifteenth-largest mobile-phone service provider by subscribers and the fourth-largest multinational after the UK's Vodafone, India's Airtel, and Spain's Telefónica.
T-Mobile is Poland's largest mobile phone network operator. The company is formally registered under the name Polska Telefonia Cyfrowa (PTC), meaning "Polish Digital Telephony", and formerly operated under the name Era until being rebranded as T-Mobile on 5 June 2011. As in other European countries, the company operates a GSM network. Following a decade-long ownership dispute with the French Vivendi corporation, the company has been wholly owned by the German telecommunications provider Deutsche Telekom since 2010.