Patent ID: 7639791

Claim:
A method, comprising: monitoring an audio signal on a telephone line with a detector and detecting an energy pulse in the audio signal on the telephone line, wherein the telephone line is connected to a telephone network of or associated with an institution, a person, or an entity; processing the energy pulse with a processor, wherein the energy pulse comprises a plurality of frequency components; determining a length of the energy pulse on the telephone line; calculating a phase for each of the plurality of frequency components to generate a plurality of phase values; generating a signal if the plurality of phase values are linear and if the length of the energy pulse is less than 40 milliseconds, wherein the signal is indicative that the plurality of phase values are linear and that the length of the energy pulse is less than 40 milliseconds, and further wherein the signal is indicative of a three-way call attempt on the telephone line; and transmitting the signal to a host computer.