| 摘要 |
PURPOSE:To discriminate a call signal for talking and a call signal for data communication in a subscriber terminal equipment side by adding a second call signal sending means to a telephone exchange. CONSTITUTION:A call signal sending circuit IRS 6 generates and sends an AC signal made by superposing a second frequency different from a first frequency on the first frequency as a call signal. A telephone set TEL 9 ansers both of call signals IRA, IRB. However, a data communication terminal DTE 10 is made to anser automatically only to the second frequency of the call signal IRB. In a TRM 8, the bell of TEL 9 is sound by the call signal IRA, and when an answer is given, communication can be made between a caller and the TEL 9. Simultaneously with ringing of the bell of the TEL 9 by the first frequency component, the DTE 10 answers automatically to the second frequency component, and the IRS 6 stops the sending of IRB, and communication data from the caller comes in automatically to the DTE 10.
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