Nippon Telegraph and Telephone West Corporation (NTT West) is one of the major companies of the NTT Group along with NTT East, NTT Communications, NTT DoCoMo, and NTT Data. NTT Corporation was established as a monopoly government-owned corporation in 1953, Nippon Telegraph and Telephone Public Corporation, privatized in 1985 to encourage competition in the telecom market. In order to weaken NTT, the company was divided into a holding company (NTT) and three telecom companies (NTT East, NTT West, and NTT Communications) in 1999. The NTT Law regulating NTT East and West requires them to serve only short distance communications and obligates them to maintain telephone service all over the country. They are also obligated to lease their unused optical fiber (dark fiber) to other carriers at regulated rates. NTT Communications is not regulated by the NTT Law.