PBX, also known as Private Branch Exchange, refers to a private telephone system used within a company or organization. Synonyms for PBX include Private Automatic Branch Exchange (PABX), Private Automated Exchange (PAE), Switchboard, and Telephone Exchange. Other related terms include VoIP PBX, IP PBX, and Hosted PBX. VoIP PBX refers to an Internet Protocol system that uses digital pathways to transmit telephone calls, while IP PBX is a PBX system that uses an Internet Protocol network. Hosted PBX, on the other hand, refers to a cloud-based PBX system that is hosted by a third-party provider. All in all, each of these synonyms for PBX refers to a private telephone system used in business settings.