A telephone central office switching system with economical application to small community dial office sizes is disclosed. Communication paths are spatially switched over a modular network fabric comprised of electromechanically actuated metallic crosspoints. A distributed control concept is employed wherein the logic power and flexibility of electronic stored program control is spread over many points in the system. Serial asynchronous messages between any two control elements are routed via a central information exchange unit whose number of communication ports is easily changed on a pluggable basis. Modularity is emphasized throughout the switching system for facile growth and additions of feature-oriented service packages.