A portable communication terminal transmits a request signal that requests voice data representing an email message, to a server apparatus when the portable communication terminal receives the email that has been sent to the portable communication terminal, and the portable communication terminal transmits the voice data received from the server apparatus, to an in-vehicle equipment. A server apparatus converts an email message that has been sent to a portable communication terminal, into voice data in response to a request signal received from the portable communication terminal, and the server apparatus returns the voice data to the portable communication terminal. The in-vehicle equipment detects a position of a portable communication terminal in a cabin, and the in-vehicle equipment outputs a voice message converted only from voice data representing an email message received by the portable communication terminal located in a specific position in the cabin, inside the cabin of the vehicle.