In-vehicle handsfree telephone system

An in-vehicle handsfree telephone system comprising:

• an in-vehicle handsfree device adapted to transfer a voice signal to a portable terminal in a passenger compartment of a vehicle;
• an operating state detection unit adapted to detect an operating state of the vehicle,
• wherein the in-vehicle handsfree device is responsive to a user operation and selectively operable in one of a handsfree mode in which talking on the portable terminal through the in-vehicle handsfree device is allowed by the transfer of the voice signal and a portable terminal stand-alone mode in which talking on the portable terminal is allowed without interference of the in-vehicle handsfree device,
• wherein the in-vehicle handsfree device is configured to have a switching restriction function in which the in-vehicle handsfree device is adapted to restrict switching from the handsfree mode to the portable terminal stand-alone mode in accordance with the operating state of the vehicle detected by the operating state detection unit, and
• wherein the mode switching operation of the in-vehicle handsfree device is performed according to a user's operation, such that:
• when the in-vehicle handsfree device is in the handsfree mode and the detected operating state indicates that the vehicle is running, the switching restriction function of the in-vehicle handsfree device is validated to restrict switching from the handsfree mode to the portable terminal stand-alone mode, and,
• when the in-vehicle handsfree device is in the portable terminal stand-alone mode and the detected operating state indicates that the vehicle is running, the switching restriction function of the handsfree device is cancelled to allow switching from the portable terminal stand-alone mode to the handsfree mode.