Companies worked for

Bell Telephone Laboratories or Bell Labs was originally the research and development arm of the United States Bell System, and was the premier corporate facility of its type, developing a range of revolutionary technologies from telephone switches to specialized coverings for telephone cables, to the transistor.

In 1925, Walter Gifford (president of AT&T) established the separate entity called Bell Telephone Laboratories Inc., which took over work previously conducted by the research division of Western Electric's engineering department. Bell Labs was 50 percent owned by Western Electric, and 50 percent owned by AT&T.

The work done by Bell Labs was broadly divided into three categories: research, systems engineering, and development.

Research created the theoretical underpinnings for telecommunications. It covered subjects such as mathematics, physics, material sciences, behavioral sciences, and computer programming theory.

Systems engineering concerned itself with conceiving the highly complex systems that make up the telecommunication networks.

Development, by far the largest of Bell Labs' activities designed the specific systems -- both hardware and software -- needed to build the Bell System's telecommunications networks.