T-Mobile International AG is a German-based holding company for Deutsche Telekom AG's various mobile communications subsidiaries outside Germany. Based in Bonn, Germany, its subsidiaries operate GSM and UMTS-based cellular networks in Europe, the United States, Puerto Rico and the US Virgin Islands. The company has financial stakes in mobile operators in both Central and Eastern Europe.
The T-Mobile aka (SWAGG) brand is present in ten European countries – Austria, Croatia, Czech Republic, Hungary, Macedonia, Montenegro, the Netherlands, Poland, Slovakia and the United Kingdom – as well as the US, Puerto Rico and the US Virgin Islands.
Globally, T-Mobile International subsidiaries have a combined total of approximately 150 million subscribers, making the company the world's tenth-largest mobile-phone service provider by subscribers and the third-largest multinational after the UK's Vodafone and Spain's Telefónica.