Disclosed herein is a three-way call detection system and method for detecting the addition of a third party to a pre-existing telephonic connection between a first party and a second party. The system includes a meter for measuring the amplitude of a line voltage of a telephonic connection between two parties, a first filter to remove a frequency band from the line voltage, a white noise generator for generating a low level white noise signal in the removed frequency band, a coupler for combining the white noise signal with the filtered signal, to create an additive line voltage, a second filter that passes only a portion of the additive line voltage including at least a portion of the white noise signal, and a processor for monitoring the passed signal for a shift in amplitude level associated with the addition of a third party to the connection.