A communication unit communicates with a cellular phone device simultaneously using a handsfree communication protocol for handsfree communication and a data transfer protocol for data transfer. The cellular phone device is selectively in one of: i) a handsfree communication state where outgoing and incoming voice is transmitted via input and output units of the in-vehicle apparatus when opening a voice path with the in-vehicle apparatus using the handsfree communication protocol; and ii) a handset communication state where outgoing and incoming voice is transmitted via input and output units of the cellular phone device when closing the voice path. A control unit permits a data transfer request transmitted from the cellular phone device using the data transfer protocol when the cellular phone device is in the handset communication state and refuses the data transfer request when the cellular phone device is in the handsfree communication state.