Operator Toll Dialing 2: Cord Signals ~ 1949 AT&T - Bell System Telephone Operator Training Film

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'Instructional film for telephone operators.' Produced for AT&T by Audio Productions.

Originally a public domain film from the Library of Congress Prelinger Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

https://en.wikipedia.org/wiki/Operator_Toll_Dialing

Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/

Operator Toll Dialing was a project and method used by the Bell System in the USA and Canada to automate the switching and billing of long distance calls in the public switched telephone network (PSTN). The program was initiated by 1945, at which time ca. 5% of the 2.7 million toll board calls per day were handled by this method.

Operator Toll Dialing eliminated the need for intermediate and inward operators to complete toll calls to distant central offices. Initially this system involved step-by-step routings to set up each circuit, but later was improved by the development of area codes with machine translation which helped to standardize dialing across the network. The system was implemented in the USA beginning in 1946. In 1947, it was integrated with the newly devised North American Numbering Plan which assigned unique area codes that served as routing codes for calls between numbering plan areas (NPAs).

Operator Toll DIaling was gradually superseded by Direct Distance Dialing (DDD), in which the customer dialed the area code followed by a seven-digit telephone number. Beginning in 1951 on a limited basis, DDD was not fully implemented until the 1970s.

Telephone administrations in other countries implemented similar programs, such as in the United Kingdom, which led to subscriber trunk dialling (STD).

https://en.wikipedia.org/wiki/Switchboard_operator

In the early days of telephony, companies used manual telephone switchboards, and switchboard operators connected calls by inserting a pair of phone plugs into the appropriate jacks. They were gradually phased out and replaced by automated systems, first those allowing direct dialing within a local area, then for long-distance and international direct dialing...

A typical telephone switchboard has a vertical panel containing an array of jacks with a desk in front. The desk has a row of switches and two rows of plugs attached to cables that retract into the desk when not in use. Each pair of plugs was part of a cord circuit with a switch associated that let the operator participate in the call or ring the circuit for an incoming call. Each jack had a light above it that lit when the customer's telephone receiver was lifted (the earliest systems required the customer to hand-crank a magneto to alert the central office and, later, to "ring off" the completed call). Lines from the central office were usually arranged along the bottom row. Before the advent of operator distance dialing and customer direct dial (DDD) calling, switchboard operators would work with their counterparts in the distant central office to complete long distance calls. Switchboard operators are typically required to have very strong communication skills.

Before the advent of automatic exchanges, an operator's assistance was required for anything other than calling telephones across a shared party line. Callers spoke to an operator at a central office who then connected a cord to the proper circuit in order to complete the call. Being in complete control of the call, the operator was in a position to listen to private conversations. Automatic, or dial, systems were developed in the 1920s to reduce labor costs as usage increased, and to ensure privacy to the customer. As phone systems became more sophisticated, less direct intervention by the telephone operator was necessary to complete calls. With the development of computerized telephone dialing systems, many telephone calls which previously required a live operator can be placed automatically by the calling party without additional human intervention...