| 摘要 |
PURPOSE:To carry out continuously an automatic selection signal transmission and a manual selection signal transmission without the omission of a selection signal and the duplication by connecting a channel when a multifrequency selection signal from an extension telephone set is interrupted. CONSTITUTION:While a private automatic branch exchange performs the automatic selection signal transmission, the multifrequency selection signal manually transmitted from the extension telephone set is temporarily stored in a selection signal memory part 104 in the private automatic branch exchange and after the automatic selection signal transmission is completed, the manual selection signal transmission information stored in the memory part 104 is successively transmitted. When the selection signal information in the memory part 104 is completely transmitted, if the multifrequency selection signal is continuously transmitted from the extension telephone set, a channel switch 105 between the extension telephone set and a trunk line 110 is not connected but the channel is connected when the multifrequency selection signal transmitted from the extension telephone set. Thereby, the automatic selection signal transmission and the manual selection signal transmission are successively carried out without the omission and the duplication of the selection signal.
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