| 摘要 |
A communication line backup system provides a backup line for backing up a communication line which connects first and second subscriber terminals. The communication line backup system includes a first backup unit which is coupled to the first subscriber terminal, a second backup unit which is coupled to the second subscriber terminal, and an integrated services digital network (ISDN) which is coupled to the first and second backup units via ISDN channels. The first and second backup units include a backup part for forming a backup communication channel between the first and second subscriber terminals in response to a failure which is generated on the communication line between the first and second subscriber terminals, and the backup communication channel is formed by at least one channel within the ISDN channels established in the integrated services digital network.
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