United States Cellular Corporation is an American mobile network operator. It is a subsidiary of Telephone and Data Systems Inc.. The company was formed in 1983 and is headquartered in Chicago, Illinois. UScellular is the fourth -largest wireless carrier in the United States, with 4,656,000 subscribers in 426 markets in 21 states as of the 2nd quarter of 2023. The organization was previously known as U.S. Cellular.