central office

In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls. A central office is the physical building used to house inside plant equipment including telephone switches, which make phone calls "work" in the sense of making connections and relaying the speech information.
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Noun
1. (usually plural) the office that serves as the administrative center of an enterprise; "many companies have their headquarters in New York"
(synonym) headquarters, main office, home office, home base
(hypernym) office, business office
(hyponym) mukataa
(classification) plural, plural form

A common carrier switching center in which trunks and loops are terminated and switched. Note: In the DOD, "common carrier" is called "commercial carrier." Synonyms exchange, local central office, local exchange, local office, switching center (except in DOD DSN [formerly AUTOVON] usage), switching exchange, telephone exchange. Deprecated synonym switch.

<communications> The place where telephone companies terminate customer lines and locate switching equipment to interconnect those lines with other networks.
(1995-03-20)