Patent ID: 8706892

Claim:
A communication system having a first server, a first terminal configured to communicate with said first server, a second server, a second terminal configured to establish a connection with said first server in a SIP protocol, wherein said first server comprises: an interface configured to receive a connection request message from the second server; a processing part configured to: establish a connection between said first terminal and said second terminal in said SIP protocol in accordance with the received connection request message; and generate a session ID concerning a session between said first terminal and said second terminal based on said connection request message; a storage part configured to store, associated with the session ID, a first session information including a first terminal IP address and a first terminal port number, a second session information including a second terminal IP address and a second terminal port number, a first server IP address and a first server port number; and a first control part configured to: receive data from said first terminal after establishment of the connection by said processing part, a destination of the data being set to the first server IP address and the first server port number, and a sender of the data being set to the first terminal IP address and the first terminal port number, acquire the second terminal IP address and the second terminal port number associated with the sender by referring to the storage part based on the sender; and transfer the data to the second terminal, the destination of the data being set to the second terminal IP address and the second terminal port number, and the sender of the data being set to the first server IP address and the first server port number.