| 摘要 |
PURPOSE:To attain calling, by providing a storage device for a specific calling telephone number and a PB tone generator to a pushbutton telephone set and hooking up a handset so as to transmit automatically the specific telephone number by PB tone. CONSTITUTION:The pushbutton telephone set 1 is connected to telephone lines 10, 11 and a PB tone memory section 23 is provided with a selecting switch group to set the telephone number and a memory IC. In hooking up the handset, hook switches 2, 16 are selected respectively to contacts 13, 18, and a DC loop circuit comprising a line 11, switch 2, handset 14, resistor 15, switch 16, hook detecting circuit 19, PB tone coupling transformer 7, and a line 10 is formed. When the detecting circuit 19 detects it, a memory section 23 is operated and a telephone number stored is read out, a PB tone generation IC 25 is controlled from a PB tone generating section 24 to generate a PB tone and the tone is transmitted to a telephone line via a coil of the transformer 7. |
