Patent ID: 8230488

Claim:
A network system, comprising: a first device; a second device; and a server device capable of registering the first device and the second device in association with each other and establishing an always-on connection session with the second device, the first device including a callback request transmission means for transmitting a callback request containing designation information on the first device on a network to the server device, a judgment means for judging whether the designation information on the first device on the network is usable, and a designation information acquisition means for acquiring designation information on the second device on the network through the server device when the judgment means judges that the designation information on the first device is unusable, wherein the callback request transmission means transmits the callback request containing the designation information on the first device to the server device when the judgment means judges that the designation information on the first device is usable, the server device including a callback request relay means for transmitting the callback request from the first device to the second device through the always-on connection session, the second device including a direct-access session establishment request means for connecting with the first device through the network on the basis of the designation information contained in the callback request received from the server device and transmitting a request for establishment of a session for direct access, and a direct-access communication means for communicating with the first device through the session for direct access.