Call monitoring system

  • Inventors:
  • Assignees: Hitachi Ltd
  • Publication Date: November 18, 1981
  • Publication Number: JP-S56149160-A


PURPOSE:To monitor sound signals of transmission and reception sides simultaneously by extracting digital sound signals in parallel from the transmission and reception sides of a bus of a time-division switch in service and by synthesizing those extracted sound signals by a voice synthesizer. CONSTITUTION:In a normal call state, a channel is composed of incoming trunk 3, bus 10 of time-division switch 1 and outgoing trunk 4 to flow sound signals of the transmission side and reception side as shown by the arrows respectively. Next, as an operator or a person in charge of maintenance sends a call monitoring request, the request is transmitted to controller 2, which holds the call state as it is and sets call-monitoring buses 10A and 10B for a multiple connection with the reception side to fetch it in operator trunk 8. Then, the digital sound signals of the transmission side and reception side extracted by buses 10A and 10B are D/A-converted in operator trunk 8 and the resulting outputs are supplied to hybrid circuit 9 to synthesize the sound signals of the transmission side and reception side so that they can be listened by receiver 7 simultaneously.




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Cited By (3)

    Publication numberPublication dateAssigneeTitle
    EP-0933913-A1August 04, 1999AlcatelMethod and device for intercepting telephone communications
    JP-S59152855-UOctober 13, 1984
    WO-2004075519-A1September 02, 2004Alain Maillet, Nicole KleinMethod and unit for interception of telephone calls