Patent ID: 8606936

Claim:
A communication system in which a plurality of IP terminals are connected to a session control management server, the session control management server comprising: a connection management table storing a status indicating talking or disconnected, calling party information and called party information; and a subscriber management table storing a telephone number, an identifier and an IP address for each subscriber; wherein, where the session control management server receives a first connection request message which is an anonymous call incoming SIP invite request, from a calling IP terminal, the session control management server extracts the calling party information and the called party information from the first connection request message received from the calling IP terminal, and registers a calling party address as the calling party information and a called terminal identifier as the called party information in the connection management table; the session control management server sends a second connection request message including the called terminal identifier and a temporary IP address assigned to a called IP terminal in the called party information to the called IP terminal; the called IP terminal device extracts the called party information from the received second connection request message and sends a response message using the temporary IP address as a self IP address to the session control management server if the temporary IP address is included; and the session control management server makes the communication between the calling IP terminal and the called IP terminal under the session connection establishment control by referring to the connection management table with the temporary IP address, wherein the session control management server further comprises a temporary IP address of a pool address management table storing a plurality of pool IP addresses, and assigns the temporary IP address by selecting the pool IP addresses in prescribed order or rule from the pool address management table.