| 摘要 |
PROBLEM TO BE SOLVED: To provide a SIP telephone device to enable users to recognize quickly that a main call control server has failures and other device performs a call control in replacement of the main call control server, and the main call control server in the state of disorder is recovered. SOLUTION: A SIP telephone device 1, which is provided with a main call control server 2 to perform a call control based on SIP and a sub call control server 3 to perform the call control in stead of the main call control server 2 when the main call control server 2 has failure, and is used in VoIP telephone system in which a telephone conversation is carried out through IP network, is provided with a memory 14 to previously memorize address information of the sub control server 3, and a control circuit 11 to indicate an error message indicating that the main call control server 2 has failure on an indicator 12 when it is found out that an IP address included in a received INVITE message in receiving calls is identical with the IP address of the sub call control server 3 stored at the memory 14. COPYRIGHT: (C)2006,JPO&NCIPI
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