| 摘要 |
PURPOSE:To limit an extension in which an incoming by a dial in can be allowed and to attain a dial in connection with the small number of digits by setting an addition number separate from an extension number to a dial in register extension. CONSTITUTION:When there is an incoming from a dial in line wire CO1, a central processing unit CCU controls a line wire trunk COT1 to automatically respond to the incoming of the line wire CO1 and transmits a tone or a message for indicating a response to the line wire CO1 through the trunk COT1. A caller connected to the line wire CO1 responds thereto to dial the addition number, and then, the unit CCU decides whether said addition number is a normal number stored in a memory M or not and when it is the normal number, identifies the extension number from said addition number to connect to a relevant extension telephone set TEL. When it is not the normal number, a disconnecting processing is executed.
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