James J. McGillan (1941-2013) was a lawyer and businessman who specialized in corporate transactions and telecommunications systems. He was co-founder of Private Transatlantic Telecommunications System, Inc. (PTAT), which constructed the first privately owned transatlantic fiber optic telecommunications cable from the United States and England. Later, he was co-founder of Med-Tel International Corp., which operated Magnetic Resonance Imaging (MRI) clinics in the U.S. and United Kingdom. McGillan's papers largely include the corporate records of both PTAT and Med-Tel International, documenting corporate buyout policies and transactions, high level executive and managerial decision making, federal licensing, and corporate law within the telecommunications industry.

MCI Communications Corporation (MCI) was a large telecommunications company. It was organized in October 1963 in Joliet, Illinois, by John D. (Jack) Goeken (1930-2010), as Microwave Communications, Inc. Goeken and his partners were planning to provide point-to-point private line microwave communications between Chicago and St. Louis to small businesses. This large collection documents the activities of the MCI Communications Corporation and its subsidiaries as well as the development of a competitive telecommunications industry in the United States and worldwide. The materials focus on MCI corporate life, public relations, technical operations, and sales and marketing activities. A vast amount of videotapes makes up a significant portion of the MCI collection, however, there are also photographs, slides, digital files, and audio cassette tapes.

MCI Communications Corporation (MCI) was one of the largest telecommunications companies in the world. It was incorporated in Delaware in 1968 as Microwave Communications of America, Inc., to provide businesses with nationwide microwave telecommunications services at low prices. Being confronted by industry de facto monopoly AT&T in the interconnection of its lines to local facilities owned by AT&T affiliated regional Bell companies, MCI challenged the telecommunications giant with competitive long-distance telephone services, both in courts and at the marketplace. MCI-AT&T antitrust litigation (1974-1985) led to AT&T's divestiture of its regional carriers and changed the previously regulated telecommunications industry into a business open to competition. The collection documents all facets of MCI history from 1968 to the end of the 1990s, as well as changes in the American telecommunications regulatory policy, legislation, and public perception of the industry. Documents also include records of MCI's subsidiaries and their predecessors starting as early as 1849.