| 摘要 |
PURPOSE:To obtain a simple function among 3-party calling without increasing largely a circuit scale by utilizing the controller of digital communication system of star connection system. CONSTITUTION:When calling is applied by any of digital telephone sets 5A, 5B, the detecting circuit 9 of a telephone set detects it and it is informed to a controller 4 from the control circuit 10 of a telephone set. Then the controller 4 supervises the information from the control circuit 10 of the digital telephone sets 5A, 5B, to switch selector switches SW1-SW3 based thereupon to control the switching of connection destination of a 2nd communication channel (transmission signal or reception signal communication channel). Thus, the function of simple 3-party calling is obtained without remarkable increase in the circuit scale.
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