Direct Distance Dialing Telephone History: "The Nation at Your Fingertips" 1951 AT&T (Patreon)

more at http://quickfound.net/

'How direct long distance dialing made the U.S. a smaller place, and how instantaneous direct communication between Americans without operator assistance became possible.' Produced 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/Direct_distance_dialing

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

Direct distance dialing (DDD) is a telecommunication service feature in which a caller may, without operator assistance, call any other user outside the local calling area. Direct dialing by subscribers typically requires extra digits to be dialed as prefixes than for dialing within the local area or within an area code. DDD also extends beyond the boundaries of national public telephone network, in which case it is called international direct dialing or international direct distance dialing (IDDD).

DDD was the term used when the North American Numbering Plan was implemented in the 1950s. In the United Kingdom and other parts of the Commonwealth of Nations, the equivalent terms are or were "STD", for subscriber trunk dialing, and "ISD" for international subscriber trunk dialing...

History

The first direct-dialed long-distance telephone calls were possible in the New Jersey communities of Englewood and Teaneck. Customers of the ENglewood 3, ENglewood 4 and TEaneck 7 exchanges, who could already dial phone numbers in the New York City area, were able to call to 11 cities across the United States, simply by dialing the three-digit area code and the seven-digit number, which at the time consisted of the first two letters of the central office name and five digits. On November 10, 1951, Englewood Mayor M. Leslie Denning made the first customer-dialed long-distance call, to Mayor Frank Osborne of Alameda, California.

The eleven destinations at that time were:

617: Boston, Massachusetts

312: Chicago, Illinois

216: Cleveland, Ohio

313: Detroit, Michigan

414: Milwaukee, Wisconsin

415: Oakland, California

215: Philadelphia, Pennsylvania

412: Pittsburgh, Pennsylvania

401: Providence, Rhode Island

916: Sacramento, California

318: San Francisco – San Francisco required the special code 318 for temporary routing requirements

Many other cities could not yet be included as they did not yet have the necessary toll switching equipment to handle incoming calls automatically on their circuits. Other cities still had either a mixture of local number lengths or were all still six-digit numbers; Montreal, Quebec and Toronto, Ontario in Canada, for example, had a mix of six- and seven-digit numbers from 1951 to 1957, and did not have DDD until 1958. Whitehorse, Yukon had seven-digit numbers from 1965, but the necessary switching equipment was not in place locally until 1972.

Hardware

The No. 4 Crossbar switching system had been introduced in the 1940s to switch four-wire circuits and replace the incoming operator. With semiautomatic operation analogous to the early days of the panel switch, the operator in the originating city used a multifrequency keypad to dial an access code to connect to the correct city and to send the seven digit number to incoming equipment at the terminating city. This design was further refined to serve DDD.

The card sorter of the 4A/CTS (Number 4A Crossbar / Card Translator System) allowed six digit translation of the central office code number dialed by the customer. This determined the proper trunk circuits to use, where separate circuit groups were used for different cities in the same area code, as in the case of Oakland and San Francisco. The new device used metal cards similar in principle to computer punched cards, and they were rapidly scanned as they fell past a light beam. CTS machines were called 4A (Advanced) if the translator was included in the original installation, and 4M (Modified) if it was added later. A 1970s version of 4XB, the 4A/ETS, used a computer to translate. For international dialing, Traffic Service Position System (TSPS) provided the extra computer power.

The reach of DDD was limited due to the inefficiency and expense of switching equipment, and the limited ability to process records of completed calls...