Vehicle information indicating the conditions of a vehicle is transmitted from an on-vehicle apparatus to an information center at least before audio guidance provided by a and IVR system (interactive voice response system) begins. The IVR system at the information center determines the level of driving load on the driver (the driving load level) based upon the vehicle information having been received and adjusts the manner with which the interactive voice response is provided based upon the determined driving load level, e.g., adjusts the speed with which the automatic audio guidance for the user is output.