An audio communication system for accommodating and transmitting audio information by unit of protocol data corresponding to a predetermined communication protocol on a network using the communication protocol, comprising audio end terminals that are sources or destinations of transmission by unit of protocol data; and a management server for managing the audio end terminals; wherein the management server has a management part for storing subscriber information indicative of whether the audio end terminals are compatible with a predetermined broadband audio communication, and wherein the management server uses the subscriber information to inform, to the users via the audio end terminals, whether the receiving telephones are compatible with the broadband audio communication, at least by the time when the users perform transmissions from the audio end terminals. This can enhance uses' satisfaction and organize a business model by which to collect tolls.