Telephonic communications – Supervisory or control line signaling – Signal reception at substation
Patent
1995-06-09
1998-02-10
Chiang, Jack
Telephonic communications
Supervisory or control line signaling
Signal reception at substation
379 93, 379 95, 379377, 379387, 379413, H04M 1100
Patent
active
057177511
ABSTRACT:
In addition to the conventional telephone portion, this telephone apparatus, coupled to a subscriber's (TEL) line coupled to an intercommunication (ICM) line, comprises a modulation circuit for modulating a data signal to have a frq band different from that used in the conventional telephone portion; a demodulation circuit for receiving/demodulating a modulated data signal having that frq band from another telephone apparatus connected to the same ICM line; and a control circuit for effecting communication with the TEL line and generating control data indicative of inhibition of using the TEL line and transmitting it as the data signal toward another telephone apparatus when the user responds a call or demodulation circuit does not receive modulated data signal indicative of inhibition of using the TEL line from another telephone apparatus. A busy tone may be supplied to the user when the user tries to use the TEL line if the control data is received by the demodulation circuit. Thus, if plural this type telephone apparatus are connected to the same ICM line, interference is prevented and each is alive in power fail because each has an interface. Further, ICM is provided with modulation signal through ICM line. A pbx having band-stop filters for preventing leaking of the ICM but transmitting control data to another ICM line is disclosed.
REFERENCES:
patent: 5361296 (1994-11-01), Reyes et al.
patent: 5400397 (1995-03-01), Ryu
patent: 5581612 (1996-12-01), Nishikawa
Yagi Hisashi
Yamanishi Kouji
Chiang Jack
Matsushita Electric - Industrial Co., Ltd.
Saint-Surin Jacques M.
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