| 摘要 |
PURPOSE:To simply attain the setting and release of holding state by providing a control circuit having a holding switch circuit, a relay controlled by the output and a holding sound source circuit. CONSTITUTION:In making the holding state, the control circuit 23 stores the holding state by the operation of a holding switch circuit 21, a relay 20 is energized to change over contacts 20-1-20-3 thereby driving the holding sound source circuit 17. In hooking on the handset in such state, the acquisition state of a telephone line is held by the contacts 12-1, 20-1 of a hook switch 12. On the other hand, a contact 12-2 is opened to store the on-hook by a control circuit 23. In releasing the holding state, the control circuit 23 release the storage of the holding state by the contacts 12-1, 12-2 by on-hook to deenergize the relay 20 thereby stopping the holding sound source circuit 17. In placing a handset 16 on a desk or the like in the holding state, the acquisition of the line is held by the contacts 20-12-1 and the holding sound is sent. In such case, the control circuit 23 is switched into the talking state by operating the switch 21 again.
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