| 摘要 |
PURPOSE:To attain hooking service like catching hone service from the telephone set of a private branch exchange system by pushing the sending button of a tone generating circuit provided at the telephone set side. CONSTITUTION:By pushing a sending button SW, a synthesizing wave is sent through connecting points SW<0> and SW<1> to a subscriber line, and received through a switch frame 4 and a trunk line trunk 5 to a hooking circuit 2. The synthesizing wave is transmitted at about -20dbm so as not to give unpleasantness to the opponent during calling, when two frequencies of frequencies f1 and f2 are detected by filters 21 and 22 of a hooking circuit 2, the AND of the detecting output is obtained by an AND gate 23, then, the pulse of 500ms-1,000ms occurs by a pulse generating circuit 24, a relay R is operated by a relaying driver 25, the trunk line is turned off and on at a connecting point (r), thus hooking action is obtained. Here, VC shows an electric power source. Thus, a hooking pulse is sent to the trunk line.
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