Abstract: Modularly Structured Digital Communications System having Operations-Oriented and Security-Oriented Components. The switching-oriented, the operations-oriented and the security-oriented components are divided into three structure levels such that apparatus program modules for generating logical switching technology messages, operating technology messages or security technology messages are provided in a line technology task structure. An operations-oriented coordination program module and switching procedure program modules for the control of the operations-oriented and of the switching-oriented information and data flow are provided in an operating technology switching technology coordination task structure. At least one operations-oriented and one security-oriented application program module for sequencing operations-oriented or security-oriented jobs are provided in an application task structure.

Abstract: Ordinary telephone sets comprising a signaling key are employed as subscriber stations in a memory-programmed telephone exchange system. Those information which respectively characterize the performance features to be activated are stored. Depending on the existence of specific switching states, the information with respect to the first of the performance features applicable thereto are transmitted to the subscriber station on the basis of the actuation of the signal key and are indicated there in a sensorally perceptible fashion as a statement regarding the respective performance feature. This indication is meaningfully comprised of the announcement of the performance feature. The memory storing the announcements, consequently, is part of a voice output device. Those voice announcements which state the performance features or services which can be activated by the subscriber are communicated to the subscriber.