private branch exchange
- noun a small telephone exchange located within a company that allows the people in the company to dial each other or to dial out to an external telephone number.
- Its abbreviation is PBX. An in-house telephone switching system that makes outside lines available to a given number of extensions in an office, group of offices, building, or the like. PBX features may include call forwarding, internal paging, call-detail recording, conference calling, caller ID, least cost routing, and reduced-digit dialing for internal calls. A PBX is subscriber-owned, and may also offer data interfaces. When call routing requires no manual intervention, also called private automatic branch exchange.