Central Office

What Does Central Office Mean?

A central office, in telecommunications, is a building to which subscriber home and business lines are connected on a local loop. This office has telephone switches to switch calls locally or to a long-distance carrier office.


This term is also known as end office or public exchange.

Techopedia Explains Central Office

Of major importance for equipment installed in a central office is uptime, network integrity, equipment compatibility and natural disaster survivability. Strict environmental and physical packaging requirements are defined by telephone service providers for telecom equipment manufacturers to ensure that switches and other central office equipment always continue to function.

The central office packaging testing requirements are defined by the Bellcore Network Equipment Building System in North America and the European Telecommunication Standard Institute in Europe. These are known as capability sets.

The central office code refers to the first three digits of local phone numbers.


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Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.