| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a telephone system which quickly and surely enables alternative transmission, an associated exchange and a transmission control method. <P>SOLUTION: An OPTIONS message is sent in broadcasting manner to all SIP servers which are included in an SIP network 100 and are accessible, and the responses are monitored to periodically monitor the state of each of the SIP servers. When any response is obtained (200 OK or error response), the state is normal. When no response is obtained, the state is abnormal, and the states of every servers are recorded in an SIP server state control table 45c. When all SIP servers are defective, an SIP trunk 45 is closed, and the state is recorded in a trunk state control table 42a. Thus, the state of trunks can be controlled in real time before an transmission request is required, an alternative transmission to a normal trunk can be issued immediately just after an transmission request is required. <P>COPYRIGHT: (C)2010,JPO&INPIT |
