Although in separate locations, the two repositories are unified operationally and exist to serve company activities. Requests from outside researchers, however, are handled on a case-by-case basis. Reputedly the largest business archives in the U.S., total holdings measure over 40,000 cubic feet of documents, books, periodicals, photographs, moving images, sound recordings, microforms, and artifacts (1869-present). The San Antonio collections are centered around the holding companies AT&T Inc. (formerly SBC Communications Inc.), Pacific Telesis Group, Southern New England Telecommunications Corp., Ameritech Corp., and BellSouth Corp. and their predecessors and subsidiaries, which primarily trace the evolution of local landline and wireless phone service in 22 states (1878-present). The Warren holdings comprise records of AT&T Corp. and its predecessor and subsidiary companies (1869-present), including Western Electric Company, Inc. (the manufacturing subsidiary renamed AT&T Technologies, Inc. in 1984 and later spun off as Lucent Technologies Inc. in 1996) and Bell Telephone Laboratories, Inc. (the famed research and development arm renamed AT&T Bell Laboratories, Inc. in 1984 and divested as Bell Labs in 1996). The AT&T Corporate Collection includes material dating from Alexander Graham Bells original inventions and the birth of the telephone industry to the present. This collection is particularly strong in material on the evolution of legacy AT&Ts business structure and policies, products, and services. The Western Electric Museum Collection and Hawthorne files includes records of Gray and Barton, the corporate predecessor of Western Electric, and thousands of photographs and documents illustrating the development of Western Electric products, plants, and people. The Bell Laboratories R&D collection documents the remarkable range of scientific and technological discoveries made since 1925 (at what is now AT&T Labs, Inc.), and includes laboratory notebooks, technical memoranda, photographs, and artifacts. Among the technical innovations documented are the transistor (John Bardeen, Walter Brattain, William Shockley), the laser, sound motion pictures, high fidelity sound recordings, early digital computers, the UNIX operating system, polymers and material science, and all aspects of telephone switching and transmission technology. Individuals represented in the collections include AT&T executives such as Theodore Vail (whose vision of one system, one policy, universal service led to the evolution of AT&Ts international telephone network), J. J. Carty (the chief engineer who turned to physicists Frank B. Jewett and Harold D. Arnold to solve the challenge of transcontinental telephone transmission using the new technology of the vacuum tube), and Walter S. Gifford (AT&T president from 1925 to 1948); Bell Laboratories executives including Frank B. Jewett (who became the first president of Bell Laboratories at its founding in 1925), H. H. Arnold, Edward Beech Craft, Oliver E. Buckley, Mervin Kelly, William Oliver Baker, John Mayo, and Ian Ross; and papers of diverse AT&T scientists and inventors, including Sidney Cyril Abrahams, Philip W. Anderson, Solomon Jan Buchsbaum, Joseph Ashby Burton, Joseph John Carty, Dawon Kahng, Rudolf Kompfner (well known for his 1943 invention of the traveling wave tube), James Brown Fisk, Calvin Souther Fuller, Lester Halbert Germer, Alan Holden, Warren Perry Mason, George Edward Moore, John Robinson Pierce (a pioneer in satellite communications), Joseph Peter Remeika, George Clark Southworth, Theodore Newton Vail, and Bells collaborator Thomas A. Watson.