| 摘要 |
PURPOSE:To attain the information of emergency independently of the state of an extension telephone set by sending an audible signal to urge the hook-on if there is an extension telephone set in permanent call state in case of simultaneous information. CONSTITUTION:In operating an operation panel 9 on emergency, a changeover contact (a) of a simultaneous information equipment 4 is switched under the control of a control circuit 8, the extension telephone set 1 is disconnected from a private branch exchange 3 and connected to the simultaneous information device 4. When the control circuit 8 detects a permanent call even after a prescribed time elapses in the extension telephone set 1, the contact (c) is turned to the position in dotted lines, and a howler tone is sent from an audible signal sending circuit 7. In detecting the hook-on of the telephone set 1, the call signal is sent.
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