When electric field strength of a reception signal becomes less than a threshold level, an in-vehicle terminal executes one of three operations. The first is that the in-vehicle terminal prohibits input of a voice. The second is that the in-vehicle terminal transmits an inputted voice with a datum indicating radio wave environment to a voice recognition server. The third is that the in-vehicle terminal once stores the inputted voice, and then transmits the inputted voice that has been stored after the electric field strength of the reception signal exceeds the threshold level.