| 摘要 |
PROBLEM TO BE SOLVED: To provide a communication system which can readily conduct connection between terminals within different local systems. SOLUTION: A terminal 11 logs in a relay server 4, and the terminal 11 updates the connection information and notifies the update to a relay server 5, when communication with the relay server 4 is available. Likewise, a terminal 21 logs in the relay server 5, and the terminal 21 updates the connection information and notifies the update to the relay server 4, when communication with the relay server 5 is available. When a connection request from the terminal 11 to the terminal 21 is transmitted to the relay server 4, the relay server 4 refers to the connection information to estimate the connection state of the terminal 21, and the fact that the terminal 21 is connected to the relay server 5. If the terminal 21 can be communicated, the relay server 4 transfers the connection request to the relay server 5, and then the relay server 5 transfers the transferred connection request to the terminal 21. Hereinafter, the relay servers 4 and 5 relay communications between the terminal 11 and the terminal 21.
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