| 摘要 |
CPU based telephone circuitry allowing for enhanced telephone functions includes a battery backup. To minimize power drain from the battery, the battery only supplies limited circuitry required for limited telephone service without CPU support. To further limit power drain, power backup circuitry includes a first circuit limited to sensing of the hookswitch status and sensing of incoming calls and generation of a ringing sound. Based on the status of the hookswitch, additional amplifiers, dialers and the like required for the limited telephone service are then powered by the backup battery.
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