| 摘要 |
PURPOSE:To simply confirm the operation of the call circuit of an extension telephone set or the lighting of a message lamp by making a central processing unit acknowledge an intra-extension calling special number, and transmitting a call signal for prescribed time from a signal generating device, when the special number is dialed from one of the extension telephone set. CONSTITUTION:The special number for an intra-extension call is registered in a storage device 4 in addition to the same as the customary one. The central processing unit 3 is made to have a function that when the special number is dialed from the extension telephone set, it acknowledges this number, and when the hand set of the said telephone set is off-hooked, it controls the signal generating device 7 so as to transmit the call signal to the said telephone set for the prescribed time. Thus, the operation of the call circuit and the lighting of a built-in message lamp can be confirmed by the extension telephone set itself, which wishes to confirm them.
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