| 摘要 |
PURPOSE: A system for verifying a public telephone and a control method thereof are provided to mount a line monitoring control unit between a main distributing frame between a public telephone line, and to generate specific information during speech, then to modulate the information to a frequency in an inaudible band for transceiving with the public telephone. CONSTITUTION: A line monitoring control unit(300) generates specific information using a frequency in an inaudible band during speech, and transmits the information to a public telephone(100) to receive response information from the public telephone(100) for analysis. If the information is incapable of being verified, the line monitoring control unit(300) forcibly disconnects a corresponding telephone line call, to limit illegal speech. The public telephone(100) analyzes the information received from the line monitoring control unit(300), and generates an authentication value capable of being verified for transmission to the line monitoring control unit(300). A telephone line(200) forms a speech path between the line monitoring control unit(300) and the public telephone(100). And a main distributing frame(400) accepts a telephone line(200) from external of a telephone station by passing the line monitoring control unit(300), in order to form a speech path between an exchange of the telephone station and the public telephone(100).
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