Telephone System/Line Analysis
Telephone Wiretap Detection and Security Inspection
Wired and wireless transmitters must be physically connected to the line before they will do any good. Once a wireless tap is connected to the line, it can transmit all conversations over a limited reception range. Wired taps, on the other hand, need no power source, but a wire must run from the line to the listener or to a transmitter.
An 'Infinity Transmitter' or 'Harmonica Bug' must be installed inside the phone. When someone calls the tapped phone it rings, blows a whistle over the line, and the transmitter picks up the phone via a relay. The mike on the phone is activated so that the caller can hear all of the conversations in the room.