PBX

a manually or automatically operated telephone facility that handles communications within an office, office building, or organization and that is connected to the public telephone network.

Compare PABX

Origin of PBX

P(rivate) B(ranch) Ex(change)

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for pbx

It is a PBX machine and is in the nature of a board up on the wall and it has several sections.
Warren Commission (10 of 26): Hearings Vol. X (of 15)|The President's Commission on the Assassination of President Kennedy

British Dictionary definitions for pbx

PBX

abbreviation for (in Britain)

private branch exchange; a telephone system that handles the internal and external calls of a building, firm, etc

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012