T-Mobile is the third largest mobile operator in the world with operations in Europe and the United States. It was founded in 1990 as Deutsche Bundespost Telekom and privatized in 1996. In the UK, T-Mobile allied with Orange to form Everything Everywhere, now rebranded as EE. In Poland, T-Mobile acquired Era, though it faced challenges with rebranding. In the US, T-Mobile merged with MetroPCS to become the fourth largest carrier by subscribers with around 42.5 million customers combined. International cooperation and mergers have helped T-Mobile grow but do not always lead to easy integration or success.