| 摘要 |
PURPOSE: A room monitoring apparatus in a key phone system having a key phone with microphone and a method therefor are provided to save a cost for security without any additional security equipment or CCTV in a place using several office rooms. CONSTITUTION: A CPU(220) controls a call switch by processing a pre-set program and also controls various services and operations. A RAM(223) includes a program and volatile data processing region, consists of multiple buffers and is used as an operation memory of the CPU(220). A ROM(225) has a control program for performing a call and a call waiting function. A switching circuit(227) switches various tones and voice data, connection between extensions, and connection of office line, etc. under the control of the CPU(220). A general subscriber circuit(229) interfaces between general phone sets of numerous subscribers and a device. A ring generator(231) outputs a square wave type ring signal to the general subscriber circuit(229). A key phone subscriber circuit(233) provides interfacing between multiple key phone sets and a device. A tone generator(235) is controlled by the CPU(220) and forms an office line loop by seizing an office line. A DTMF receiver(239) analyzes a DTMF signal generated from the subscriber of the general subscriber circuit(229) or from an office line circuit. A DTMF transmitter(241) outputs a DTMF signal to the switching circuit(227) under the control of the CPU(220). A clock circuit(221) provides a clock function to the CPU(220) and performs a timer function to count predetermined time.
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