| 摘要 |
PROBLEM TO BE SOLVED: To hold calling just before entering an incommunicable area and to prevent an interruption in the course of communication by estimation whether a vehicle reaches an incommunicable area in a prescribed time from a current location based on an incommunicable area data. SOLUTION: If it is determined based on the outputs of a vehicle speed sensor and a parking brake sensor, that a vehicle is traveling, and if a calling is not held, a decision is made whether the vehicle will reach an incommunicable area such as a tunnel or not after a time ΔT from a current position based on a navigator information taken into a navigator take-in part 24b, incommunicable area data and a sensor output to an inputting part 24a. If a decision result is YES, calling is held in order to prevent a sudden interruption in an incommunicable area. Also a message sending means 23 is controlled and a prescribed message that calling is held is sent to a driver. |
