When terminals perform communication through a reservation, a management unit manages terminal identification information identifying each terminal and reservation identification information identifying the reservation. When a first terminal performs communication through a predetermined reservation, a receiving unit receives, from the first terminal, a request to acquire state of a second transmission terminal. A reservation extracting unit extracts the reservation identification information associated with terminal identification information identifying the second terminal from the management unit. A determining unit determines whether the reservation identified by the extracted reservation identification information matches the predetermined reservation. A transmitting unit transmits first state information indicating first state of the second terminal to the first terminal when the determining unit determines that the reservation matches the predetermined reservation, but transmits second state information indicating second state of the second terminal when the determining unit determines that the reservation does not match the predetermined reservation.