Centrex

This article is about the type of telephone exchange. For the British police training agency, see Centrex (police training agency). For the Gazprom-related group of companies, see Centrex Europe Energy & Gas AG.
Typical standard phone used with Centrex. Note the "Recall" button and the Message Waiting Lamp.

Centrex is a portmanteau of central exchange, a kind of telephone exchange. It provides functions similar to a PBX, but is provisioned with equipment owned by, and located at, the telephone company premises.[1]

Centrex service was first installed in the early 1960s in New York's financial district by New York Telephone.[2][3] As of 2003,[needs update] it was estimated that there were 20 million Centrex lines installed worldwide by 20 telephone companies, with the most installations in the United States (15 million), Canada (2 million), and the United Kingdom (1 million).[2] This accounted for approximately 5% of all installed business telephone lines, worldwide.[2]

In terms of user-visible features, Centrex and PBX are similar. Features include:[4]

  1. ^ Wittenberg, Nicholas (2009-02-19). Understanding Voice Over IP Technology. Cengage Learning. p. 367. ISBN 9781111806613.
  2. ^ a b c Abrahams, John R.; Lollo, Mauro (2003). Centrex Or PBX: The Impact of IP. Artech House. Chapter 1, Introduction to Centrex. ISBN 9781580536226.
  3. ^ "Telephony 101: Centrex". The Museum of Telephony. 2016-07-09. Retrieved 2019-01-04.
  4. ^ Horak, Ray (2012-11-19). Telecommunications and Data Communications Handbook. John Wiley & Sons. Section 3.3.1 (Features). ISBN 9781118585801.