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Telephone wire tapping

     This very simple circuit can be listen to what people on telephone talk. Just connect it to your phone wire (line). The line has 4 wires, but only 2 of then are interesting. In the flat cable they are in the middle: the green and the red. The telephone wire tapping circuit is connected to those two wires (polarity does not matter). Values of components are not critical at all, you can use twice more or twice less the value. Transistor is for example BC547, BC548, KC507, KC508, BC237 or BC238. The power supply is a 9-Volt battery.

     Warning: It is illegal to connect any device that is not approved, especially wire listening devices, to the telephone network!! This article is intended only to draw attention to the potencial danger of being telephone wire tapped. I do not encourage anybody to build or even use this device! I do not take any responsibility for any material or immaterial damage, which may be causes by the device. Its use creates the risk of legal sanctions. The telephone line may contain hazardous voltages. Everything you do at your own risk.

Telephone wire tapping circuit schematic.

Added: 2002