Monitoring system

A monitoring system, comprising:

• a plurality of terminal devices configured to be capable of communicating with each other;
• a center device configured:
• if receiving a first request from a terminal device at a specified time schedule, to return a first response including request information with respect to the terminal device;
• and thereby
• to transmit the request information to the terminal device,
• wherein the center device comprises a designation response means configured, when receiving a first request from any of the terminal devices, if having request information to be sent to another terminal device, to return a first response including designation information designating said another terminal device,
• wherein each of the terminal devices comprises:
• a designation notice means configured, when the designation information is included in the first response from the center device, to transfer the designation information to said another terminal device;
• and
• an interruption processing means configured, if receiving designation information designating the terminal from a different one of the terminal devices, to transmit a second request to the center device.