Patent ID: 8205074

Claim:
A data communication method for communication between a client and a destination server via a communication network to which session management servers are connected, comprising: a first step of sending from said client to first one of said session management servers a query, in which a known destination identifier of a destination server is specified, to request retrieval of a corresponding resource identifier including a domain name assigned to the destination server; a second step of retrieving by said first one of said session management servers, a resource identifier of said destination server corresponding to the known destination identifier of said destination server from an identification information management table indicating the correspondence of destination identifiers to resource identifiers, and notifying said client of the resource identifier; a third step of transmitting a connection request message from said client to said first one of said session management servers, said connection request message designating a request resource with the resource identifier of said destination server; and a fourth step of determining, by said first one of said session management servers having received the connection request message, a forwarding destination of the received connection request message based on a domain name included in the resource identifier specified in the received message, and forwarding the received message to the destination server or second one of said session management servers managing a domain to which the destination server belongs, and said first and second one of said session management servers are Session Initiation Protocol servers.