AA916 combines all the essential functions needed for effective internal communication in one compact unit: hands-free loud-speaking soft-speaking, and confidential total privacy. It is designed for a desk use or wall-mounting using an optional wall bracket (model GF933). On the desk or wall, it permits the user to converse with the caller, hands-free, from anywhere in the room. Master is designed to work with the RM5000EX or CB901EX series microprocessor intercom systems.