Abstract: In a system for the transaction operation with terminal units connected to a central unit through the communication line, the transaction operation by use of an ineligible terminal unit is prevented. An illegality preventive information is provided for each terminal unit and stored in each terminal unit and the central unit. When the terminal unit transmits transaction data to the central unit, it also transmits the illegality preventive information registered in it. The central unit carries out the transaction process when the received illegality preventive information coincides with or has a certain relationship to the registered information.

Abstract: In a system having a central unit, a terminal control equipment and terminal devices connected through communication lines, a transaction operation by an unauthorized terminal device is prevented.Unauthorized use prevention information is registered to each of the terminal devices and the unauthorized use prevention information of the respective terminal devices is registered to the terminal control equipment. The terminal device, when it transmits transaction data to the terminal control equipment, transmits the unauthorized use prevention information of its own. The terminal control equipment compares the received unauthorized use prevention information with the registered unauthorized use prevention information of the corresponding terminal device and, if they are in a predetermined relation, permits the transaction operation.

Abstract: A method of and an apparatus for detecting the all make busy state of a line concentrator or an exchange in which all outgoing circuits are divided into a plurality of groups, at least one circuit is specified from each of the groups, the specified circuits are successively scanned with a scanning signal producing therefrom a plurality of phase pulse signals having phase ranges resulting from dividing phase ranges by at least the number of the specified circuits of the groups corresponding to the latter phase ranges which are one period of the scanning signal divided by the number of the groups, the busy state of the specified circuit of a group is detected to decide the busy state of the group, and the busy states of all groups at one cycle of the scanning are detected to detect the all make busy state of the line concentrator or the exchange.