Advanced three way call detection system and method using spread spectrum techniques

摘要

An advanced three way call detection system which measures delay times associated with multiple echoes of a reference signal transmitted over a two way call. A reference signal is initially transmitted over a two way call when a two way connection is first established between a local telephone and a remote telephone. The echo characteristics of the two way connection are measured and recorded in an initial echo profile. The initial echo profile represents the number of and timing of each detected echo of the reference signal after transmission of the reference signal over the two way call when the two way connection is first established. The reference signal is then continuously transmitted at various timing intervals during the telephone conversation and the incoming line is sampled in order to detect echoed versions of the reference signal in order to create subsequent echo profiles. Whether a three way calling event has occurred is determined by virtue of changes in the delay times and number of echoes in each subsequent echo profile when compared with the initial echo profile.