US West, Inc. (stylized as US WEST) was one of seven Regional Bell Operating Companies (RBOCs, also referred to as "Baby Bells"), created in 1983 under the Modification of Final Judgement (United States v. Western Electric Co., Inc. 552 Fed. Supp. 131), a case related to the antitrust breakup of AT&T. US West provided local telephone and intraLATA long-distance services, data transmission services, cable television services, wireless communications services and related telecommunications products to defined areas in Arizona, Colorado, Idaho, Iowa, Minnesota, Montana, Nebraska, New Mexico, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming. US West was a public company traded on the New York Stock Exchange under the ticker symbol "USW" with headquarters at 1801 California Street in Denver, Colorado. Until 1990, US West was a holding company with three Bell Operating Companies: Mountain States Telephone & Telegraph (or Mountain Bell, headquartered in Denver, Colorado); Northwestern Bell, then headquartered in Omaha, Nebraska; and Pacific Northwest Bell, then headquartered in Seattle, Washington. In 1988, the three companies began doing business under the US West Communications name. On January 1, 1991, Northwestern Bell and Pacific Northwest Bell were legally merged into Mountain Bell which was renamed US West Communications, Inc. US West was the first RBOC to consolidate its Bell Operating Companies (the other was BellSouth). In 1998, US West split into two separate companies. Its telephone properties maintained the US West name, while the remaining assets such as cable, wireless and international businesses became MediaOne. The split was structured so that MediaOne Inc. was the legal successor to US West Inc., and US West was the spin-off entity. US West merged with Qwest on June 30, 2000, and over time the US West brand was replaced by the Qwest brand. Qwest merged with CenturyLink on April 1, 2011, and the Qwest brand was replaced by the CenturyLink brand. Accomplishments US West became a pioneer in the introduction and rapid system-wide implementation of telephone technologies designed by Bellcore (now Telcordia Technologies) in the 1980s and 1990s. Their lead in this push became one that many other Regional Bell Operating Companies had to scramble to keep up with. US West's success in this endeavor was for multiple reasons which included their then-innovative use of "test-markets" for staggered roll-outs of new calling features in middle-sized cities such as Boise, Idaho, Minneapolis, Minnesota, and Phoenix, Arizona before releasing them on a wider scale.