| 摘要 |
PURPOSE:To prevent a dial in connection by an arbitrary dial operation of the caller of a line wire by setting a password number to the line wire to which a dial in service is applied. CONSTITUTION:When an incoming is present from a dial in line wire CO1, a central processing unit CCU transmits a tone or a message indicating a response to the line wire CO1 through a line wire trunk COT1. The caller connected to the line wire CO1 dials the password number set for the dial in connection according to this tone or the message. The unit CCU examines whether said password number coincides with a password number stored in a memory M or not and when they coincide, it dials an extension number to connect to a telephone set TEL in question. When they do not coincide, a disconnecting processing is executed.
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