| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an IP telephone network which allows services to be performed between bases without user's paying his or her attention to an outside line number even in the case that communication between the bases is impossible. <P>SOLUTION: Extension number-outside line number tables 16, 26, and 36 wherein extension numbers including extension numbers between the bases 1 to 3 and outside line numbers corresponding to them are stored are arranged in each of bases 1 to 3 correspondingly to a communication control device 11 and communication control devices 21 and 31 for backup. In the case that normal extension calls between the bases 1 to 3 are impossible due to the occurrence of a fault of the IP network 100, the communication control device 11 and communication control devices 21 and 31 for backup respectively switch the extension calls between the bases 1 to 3 to connections passing a line switching network 200 on the basis of information of extension numbers-outside line numbers preliminarily set in the extension number-outside line number tables 16, 26, and 36. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
