Cingular was founded in 2000 as a joint venture between SBC Communications and BellSouth, merging their respective wireless operations. It quickly became one of the largest mobile service providers in the United States. In 2004, Cingular acquired AT&T Wireless, further expanding its subscriber base. In 2007, Cingular rebranded itself as AT&T Mobility after AT&T Inc. acquired BellSouth, ultimately integrating the Cingular brand into the AT&T brand.