A PBX system provides businesses with the necessary functions and features exclusive to business requirements instead of a residential landline or mobile phone, for example. Some of those features might include the ability to manage multiple inbound or outbound calls, offer individual extensions for employees, auto attendants and general business call management features, which would be surplus to requirements in a residential or mobile system. Different types of PBX use different communications channels, including voice over internet protocol (VoIP) and integrated services digital network (ISDN).

These business telephone systems are specifically designed to meet the needs of the modern business in connecting it with the outside world and are differentiated from residential services on account of the features they have the propensity for. Typical PBX features include call routing, call queuing, conference calling, auto attendants and hold music capabilities, among many other functions, as well as simply making and taking phone calls.