Glossary definition of PBX

Also known as: Private Branch Exchange

Private Branch Exchange (PBX) is a privately owned and operated telephone exchange system of the type usually found in offices and companies. Such exchanges can switch calls between the extensions within the organisation, and they are also used to connect users to external phone lines for calls to destinations outside the company.

Normally the exchange shares a limited number of external phone lines between all users, because at any one time the internal traffic will be greater than calls going outside the organisation.

Most PBXs now use digital technology, and in practice most PBXs are automatic i.e. PABX.