Patent ID: 7366146

Claim:
A data communication system comprising: a server which provides a service through a communication network; a data link starting side apparatus which makes a line connection request from an originating telephone number; a data link started side apparatus connecting to said data link starting side apparatus via a circuit switched network, which data link started side apparatus holds the originating telephone number of the line connection request, performs line control between said data link started side apparatus and said data link starting apparatus by connecting said link starting side apparatus to said data link started side apparatus via a line of the circuit switched network, and performs LAN control between said data link started side apparatus and said server through the communication network, thereby relaying a packet between said link starting side apparatus and said server; the data link starting side apparatus which is line-connected to said data link started side apparatus through the circuit switched network, disconnects the line between said data link starting side apparatus and said data link started side apparatus on the basis of an MITF dial-up dormant protocol when there is no communication between said data link starting side apparatus and said server for a predetermined period of time, and shifts to a dormant state in which a link at a physical layer level is released; and an originating server which originates data reception notification to said data link starting side apparatus by using the originating telephone number transmitted from said data link started side apparatus as a notification destination number when a packet communication state between said data link starting side apparatus and said data link started side apparatus is in the dormant state, and said data link started side apparatus receives data addressed to the data link starting side apparatus from said server.