| 摘要 |
PROBLEM TO BE SOLVED: To provide a call recorder of a telephone set, which is capable of satisfactorily recording telephone calls in both transmission and reception irrespective of peripheral sounds input by a transmission part even when the telephone set is connected to a digital line. SOLUTION: Effective sound signals of a call transmission part 3 and a call reception part 4 are detected by a sound sensing part 19. Sound signals of the call transmission part 3 and the call reception part 4 which are sent to the sound sensing part 19 are attenuated by an attenuator. An attenuation amount switch 18 is operated so as to send the sound signals to the sound sensing part 19 while switching an attenuation amount. A control part 10 causes the attenuation amount switch 18 to switch the attenuation amount so as to reduce the attenuation amount of sound signals and starts recording a telephone call when the sound sensing part 19 detects the effective sound signal of the transmission par 3 or the reception part 4, and the control part 10 causes the attenuation amount switch 18 to switch the attenuation amount so as to increase the attenuation amount of sound signals and starts recording a telephone call when a state where the level of sound signals is equal to or lower than a prescribed level continues for a prescribed time. COPYRIGHT: (C)2009,JPO&INPIT
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