No. 4 ESS: Mass Announcement Subsystem

Provision of the mass announcement capability on the No. 4 Electronic Switching System (ESS) requires the system to record and store voice announcements, and to play them back to large numbers of calling customers. The capability of instantaneously creating multiple copies of an announcement and distributing the copies to many callers is inherent in the design of the No. 4 ESS digital switching network, 1 and is a principal reason for choosing No. 4 ESS as the vehicle for the mass announcement service. Recorded announcement hardware already in No. 4 ESS lacked the capacity and features needed, so a new hardware subsystem was designed. This paper describes the hardware subsystem portion of the No. 4 ESS mass announcement capability. An overview of the entire capability, including No. 4 ESS processor software and interactions with the telephone network, appears in a companion paper. 2 Architecture of the new mass announcement subsystem is influenced by the existing No. 4 ESS architecture and interfaces, and the functional 1083