| 摘要 |
PURPOSE: A device for using automatically a private line of a telephone is provided to construct a database for the private lines of each region, central offices and oversea lines, and to dial an only central office number. CONSTITUTION: A database(120) stores data of a private line in respond to central office data. A controller(130) compares the central office data with the private line data, and decides whether a private line corresponding to the central office exists. An exchange unit(140) switches the central office and the private line according to a control signal of the controller(130).
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