PBX - Private Branch Exchange

    A business telephone system refers to any of a range of a multiline telephone systems typically used in business environments, encompassing systems ranging from small key systems to large scale private branch exchanges. A business telephone system differs from simply using a telephone with multiple lines in that the lines used are accessible from multiple telephones, or "stations" in the system, and that such a system will often provide additional features related to call handling. Business telephone systems are often broadly classified into "key systems", "hybrid systems", and "private branch exchanges".