PBX stands for Private Branch Exchange and is the most common telecommunications system in most businesses. PBX allows companies to make and take inbound and outbound calls, set up voice mail, reroute calls between phone units, and many more call management features. It’s mostly used to switch calls between a telephone network and an office.
Other features include making calls over VoIP (Voice over IP), ISDN, on-hold music or messages, and, depending on your provider, find-me-follow-me services for companies with mobile employees.