| 摘要 |
A portable telephone for controlling the production of a musical tone and incoming call sound according to the class of incoming call-related telephone numbers. Specifically, a portable telephone produces, for a first-class telephone numbers, an incoming call signal while stopping a musical tone, and, for a second-class telephone numbers, gradually reduces the sound volume of a musical tone. For a third-class telephone numbers, it continuously produces a musical tone without interruption and automatically cuts off the circuit without producing an incoming call sound.
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