JPS5731255A - Automatic tracking system of call subscriber - Google Patents

Abstract

PURPOSE:To automatically track and catch a calling subscriber who calls another subscriber with an evil intention, by securing an automatic tracking and catch of the malicious calling subscriber for a maintainer of a telephone office even in case the call given by a subscriber of another office is detected through a trace-back of the call. CONSTITUTION:A maintainer in a telephone office registers the number of a subscriber SUBB who previously requested a trace-back of call through a typewriter. The exchange office EL2 storing the SUBB transmits both the telephone number of the SUBB and the calling subscriber tracking indication signal to an upper repeater station ET. The ET transmits the information to all exchange occices EL1- under the control of it, and the EL1 registers the information in a memory MEM1. When an optional subscriber SUBBA1 calls, the checking is carried out to know whether the telephone number of the called subscriber coincides with the number of the SUBB registered in the MEM1. When a conincidence is obtained between these two numbers, the numbers of both SUBA1 and SUBB are delivered to the TYP of the EL1 to be informed to the maintainer via the EL. These transmissions and receptions of signals are carried out through common line signal devices DT10, DT20 and DT30 respectively.