| 摘要 |
PROBLEM TO BE SOLVED: To achieve voice communication between IP telephone sets by using a simple and inexpensive configuration, irrespective of the type of NAT of a relay apparatus. SOLUTION: The relay terminal C is used in an IP telephone system 1 having a plurality of IP telephone terminals A, B connected to NAT routers A, B and an SIP server 2. The relay terminal C supports a normal mode for voice communication with an IP telephone set and a relay mode for relaying voice communication between the other IP telephone sets and is provided with: a relay terminal registering section 15 for instructing the SIP server to transfer an SIP message transmitted/received between the IP telephone sets in the relay mode; an SIP message relay section 17 for rewriting the IP address and port number of a communication destination of voice communication included in the SIP message transferred from the SIP server to the IP address and port number of its own apparatus and returning them to the SIP server; and an audio packet relay section 19 for relaying voice communication between the IP telephone terminals after connection between the IP telephone terminals has been established. COPYRIGHT: (C)2009,JPO&INPIT
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