A voice over Internet (VoIP) service that is provided by a third party for businesses with a small to medium number of phone extensions. All calls are transported over the Internet, and telephone functions such as voice mail, call routing and call forwarding are performed on the provider's computers. Administration is handled via a Web interface.

Calls can be made and received using regular phones with adapters, IP phones or computers. A hosted VoIP service provides a "virtual IP PBX" for an organization without requiring a physical PBX. See IP CENTREX, VoIP, IP PBX, IP phone and analog telephone adapter.