Circuit arrangement for a special telephone system formed from a centrally controlled extension part and a centrally controlled operating part (operating connection line registering device)

摘要

For the extension and operating subscriber devices, the special telephone system (FSA) has telephone devices (SPE) of the same type which are in turn connected to the switching network (KF) of the special telephone system (FSA) which is common to the extension part and the operating part. Furthermore, the main connection lines (HAL), the operating connection lines (BAL) and the switchboard equipment (VPE) are connected to the switching network. The switching network (KF) of the special telephone system (FSA) is controlled by the central control device (ZST) which activates the operating connection line registering device (BAR) for charge calculation only when the operating connection lines (BAL) are seized. Special telephone systems of this type are required, inter alia, for power supply companies. IMAGE