Face of a 1939 rotary dial showing the telephone number LA-2697, which includes the first two letters of Lakewood, New JerseyEducational film produced by Bell which explains the correct use of a dial telephone, using WOrth 49970 as an example number
A telephone exchange name or central office name was a distinguishing and memorable name assigned to a central office. It identified the switching system to which a telephone was connected, and facilitated the connection of telephone calls between switching systems in different localities.
While small towns and rural areas might each be served by a single exchange, large cities were served by multiple switching systems, either distributed in the community constituting multiple exchange areas, or sometimes hosted in the same building to serve a densely populated area. Central offices were usually identified by names that were locally significant. The leading letters of a central office name were used as the leading components of the telephone number representation, so that each telephone number in the area was unique. These letters were mapped to the digits of the dial, which was indicated visibly on the dial's numbering plate.
Several systematic telephone numbering plans existed in various communities, typically evolving over time as the subscriber base outgrew older numbering schemes. A widely used numbering plan was a system of using one or two letters from the central office name with four or five digits. Such systems were designated as 2L-4N or 2L-5N, or simply 2–4 and 2–5, respectively, but some large cities initially selected plans with three letters (3L-4N). In 1917, W. G. Blauvelt of AT&T proposed a mapping system that displayed three letters each with the digits 2 through 9 on the dial.[1]
Telephone directories or other telephone number displays, such as in advertising, typically listed the telephone number showing the significant letters of the central office name in bold capital letters, followed by the digits that identified the subscriber line. On the number card of the telephone instrument, the name was typically shown in full, but only the significant letters to be dialed were capitalized, while the rest of the name was shown in lower case.
Telephone exchange names were used in many countries, but were phased out in favor of numeric systems in the 1960s. In the United States, the demand for telephone service outpaced the scalability of the alphanumeric system and after introduction of area codes for direct-distance dialing, all-number calling became necessary. Similar developments followed around the world, such as the British all-figure dialling.
^M. D. Fagen, ed. (1975). A History of Engineering and Science in the Bell System: The Early Years (1875-1925). Bell Telephone Laboratories. p. 578.
and 25 Related for: Telephone exchange names information
A telephoneexchangename or central office name was a distinguishing and memorable name assigned to a central office. It identified the switching system...
A telephoneexchange, also known as a telephone switch or central office, is a crucial component in the public switched telephone network (PSTN) or large...
the originating telephone set, which transmits the sequence of digits in the process of signaling to a telephoneexchange. The exchange completes the call...
London had a large network of manual exchanges (80 in 1927) and individual telephoneexchanges were given names, e.g. Ebbsfleet; a caller asked the operator...
leading letters of telephoneexchangenames. In the mid-20th century United States, before the switch to All-Number Calling, telephone numbers had seven...
(KTS) to the private branch exchange (PBX). A business telephone system differs from an installation of several telephones with multiple central office...
Anchor Exchange was an underground, hardened telephoneexchange built in Birmingham, England. Construction commenced in 1953 under the guise of building...
electromechanical stepping switch telephoneexchange system. It was developed by the Strowger Automatic TelephoneExchange Company founded in 1891 by Almon...
A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony...
dialing. It is used when initiating a telephone call to transmit the destination telephone number to a telephoneexchange. On the rotary dial, the digits are...
20th century. The switchboard was an essential component of a manual telephoneexchange, and was operated by switchboard operators who used electrical cords...
a toll call. Despite the abandonment of telephoneexchangenames in telephone numbering plans, many telephone dials and keypads maintain a tradition of...
Telephone numbers in Japan consist of an area code, an exchange number, and a subscriber number. 001, 00xx, 002xx, 0091xx Carrier selection prefix 184...
number may have different lengths. It shows which exchange the remaining numbers refer to. A full telephone number is usually made up of a country code (required...
of the telephone chronicles the development of the electrical telephone, and includes a brief overview of its predecessors. The first telephone patent...
with telephoneexchangenames followed by digits, such as in the telephone number "PEnnsylvania 6-5000". The letter Z appeared on many telephone dials...
The Pacific Bell Telephone Company (Pac Bell) is a telephone company that provides telephone service in California. The company is owned by AT&T through...
Hungarian engineer Tivadar Puskás proposed the telephone switch, which allowed for the formation of telephoneexchanges, and eventually networks. In the United...
telegraph and telephone services). Telephone companies are common carriers, and in the United States are also known as local exchange carriers. With...
The Nippon Telegraph and Telephone Corporation (NTT) (Corporate Number: 7010001065142) is a Japanese telecommunications holding company headquartered...
national dialling codes. Exchangenames were usually closely tied to the physical location of telephoneexchanges, being either the name of a city, town or...
telephone systems took advantage of the exchange principle already employed in telegraph networks. Each telephone was wired to a telephoneexchange established...
A telephone directory, commonly called a telephone book, telephone address book, phonebook, or the white and yellow pages, is a listing of telephone subscribers...
or territory. All local telephone numbers within the four areas have eight digits, consisting (mainly) of a four-digit exchange code and a four-digit local...
Global Information