| 摘要 |
A system and method is provided for automatically connecting and disconnecting alternative power to intercom telephones without interfering or interacting with the power supplied or cancelled by the telephone company central office. Central Office power is continuously monitored by a sensing circuit to determine whether the service to that telephone is being activated or deactivated by the Central Office. When no Central Office power is detected, the system automatically supplies alternative operating power to the telephone, enabling it to initiate intercom phone calls. When a resumption of Central Office service is detected, the power supplied by the system is removed, and the Central Office power is supplied to the telephone.
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