| 摘要 |
PURPOSE: An SIP(Session Initiation Protocol) server and a communication method between SIP terminals using the same are provided to allow call communication between SIP terminals positioned in a private network and in a private network or in a public network and in a private network without installing an additional function in an existing data network. CONSTITUTION: When a 'register' message is received from an origination SIP terminal, registration is performed, and then, when the registration is completed, a '200 OK' message is re-transmitted to the origination SIP terminal(S1). When an 'INVITE' message is received from the origination SIP terminal, a call connection request is transmitted to a receiver SIP terminal, and if line of the receiver SIP terminal is busy, a '180 Ringing' is re-transmitted, and then, when the receiver SIP terminal accepts media session information and allows call connection, a '200 OK' message and 'ACK' are re-transmitted(S2). An RTP(Real-time Transport Protocol) message is relayed between the origination SIP terminal and the receiver SIP terminal through the connected call and accepted media session information(S3).
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