RIDING DETERMINATION PROGRAM, TERMINAL DEVICE, COMMUNICATION SYSTEM, AND RIDING DETERMINATION METHOD

A terminal device includes a communication unit configured to communicate with a communication device used in a vehicle and a control unit configured to determine whether a user is in the vehicle when a signal sent from the communication device is received via the communication unit, according to at least one of whether a destination has been set by the user and whether a vehicle dispatch application is activated. The vehicle dispatch application is a program for receiving a vehicle dispatch service.