| 摘要 |
PURPOSE:To simultaneously have a conversation between many persons receiving incoming call by adding a circuit to mix the sound signal of plural receiving lines to a private branch exchange capable of the dial-in connection. CONSTITUTION:When the private branch exchange 3 dial-in-connects the incoming call from a general telephone set 1, collates it with the memory contents 15 and 16 of a memory part 6 and detects that it is a call to a telephone square, the device connects an incoming call line to talkie equipment 9, and after the equipment transmits that the line is connected to a telephone field, the equipment in connected to a sound mixing circuit 8a. Then, the conversation can be simultaneously executed between plural lines received to the telephone field. When the incoming call is increased or decreased, a participating audible sound signal circuit 11 or a separating audible sound signal circuit 12 is once connected to a sound mixing circuit 8a, and it is informed that there are the persons to participate in or separate from the telephone field. At the prescribed period, the information linked to the profit of an exchange owner such as advertising can be flowed to the telephone field.
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