T-Mobile USA, Inc. is a mobile network operator headquartered in Bellevue, Washington, United States that provides wireless voice, messaging and data services in the United States, Puerto Rico and the U.S. Virgin Islands. T-Mobile USA is the fourth-largest wireless carrier in the U.S. market with 33.73 million customers and annual revenues of US$21.35 billion in 2010. As of 2011, J.D. Power has ranked T-Mobile USA highest among major wireless carriers for retail store satisfaction four years consecutively and highest for wireless customer care two years consecutively.

T-Mobile USA traces its roots to the 1994 establishment of VoiceStream Wireless PCS as a subsidiary of Western Wireless Corporation. Western Wireless spun off VoiceStream Wireless to shareholders on May 3, 1999, creating an independent company, VoiceStream Wireless Corporation, that traded on the NASDAQ under the ticker symbol VSTR. VoiceStream Wireless acquired Omnipoint Communications in February, 2000 and Aerial Communications in May, 2000. On June 1, 2001, Deutsche Telekom AG completed the acquisition of both VoiceStream Wireless Corporation for US$35 billion and Powertel, Inc. for US$24 billion. Deutsche Telekom renamed VoiceStream Wireless Corporation in July, 2002, giving the company its current name, T-Mobile USA, Inc. T-Mobile USA, Inc. is the United States operating entity of T-Mobile International AG, the mobile communications holding company and subsidiary of Deutsche Telekom AG.

On March 20, 2011 Deutsche Telekom accepted a US$39 billion stock and cash purchase offer for T-Mobile USA from AT&T Inc. If completed, the acquisition will create the largest wireless carrier in the United States, with nearly 130 million customers. The acquisition is subject to regulatory and shareholder approval and is expected to close in March 2012.