| 摘要 |
PROBLEM TO BE SOLVED: To provide a private branch exchange system with high reliability capable of continuing communication (speech) by using a particular extension terminal and a particular public line at all times wherein the particular extension terminal and the particular public line are connected to two private branch exchanges via a switching unit, even when one of the private branch exchanges is defective, the other private branch exchange backs up the particular extension terminal and the particular public line by switching the switching unit. SOLUTION: The private branch exchange system comprises: a master private branch exchange 2; a slave private branch exchange 3; the particular extension terminal 4 being a backup object and the switching unit 5a; the particular public line L1 being a backup object in a public network NT and a switching unit 5b; and lines La, Lb for interconnecting the master private branch exchange 2 and the slave private branch exchange 3 for communication (speech). COPYRIGHT: (C)2007,JPO&INPIT
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