| 摘要 |
PROBLEM TO BE SOLVED: To set a transfer destination in a busy state in advance to each extension terminal. SOLUTION: The key telephone system is provided with a master device 1 and extension terminals 10-14 that are connected to the master device 1 via an extension 60. The master device 1 is provided with an extension terminal interface circuit 2 that extracts digital voice data and control data from the extension terminals 10-14, a time division switch 3, a DTMF sender 4 that transmits a DTMF signal to the extension terminals 10-14 and an external line (not shown in figure), a DTMF receiver 5 that measures a reception level of the DTMF signal received from the extension 60 to provide an output of the detection result of the DTMF signal, a control circuit 6 that controls the entire master device 1, and a memory 7 that stores a table of extension numbers rearranged in the order of higher reception levels. The extension terminals 10-14 are configured with loudspeakers 20-24 that output the DTMF signal and microphones 30-34 that receives the DTMF signal and returns it to the master device 1.
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