"The telephone at your elbow seems so simple an instrument, it does its work so quietly, that it is difficult to realize the vast and complex equipment, the delicate and manifold adjustments, the ceaseless human care 'behind the scenes' in the central offices..." Guardians of the circuits. The Bell system. AT&T, American Telephone and Telegraph Company and associated companies. One policy, one system, universal service, and all directed toward better service. 1922 advertisement. Click here to enlarge. "It is the skill of the men behind the scenes, together with scientific development and construction, efficient maintenance and operation, which make it possible for you to rely upon the telephone day and night."