| 摘要 |
A radio telephone set comprises switch circuitry (51), a telephone circuit (71) and a battery (81) for portable operation, which battery may be a built-in battery. When the radio telephone set is not mounted on a vehicle, the switch circuitry is not connected to a battery of the vehicle and feeds power from the built-in battery to the telephone circuit. Thus, the radio telephone set can be used as a portable set. When the radio telephone set is mounted on the vehicle, the switch circuitry is connected to the vehicle battery and this connection causes the automatic switching of the power supply to the telephone circuit from the built-in battery to the vehicle battery. Thus, the radio telephone set can be used as a vehicle-mounted, or onboard, set. |
