Three-way call detection using steganography

A method for identifying a source telephone, the method comprising:

• providing a data identification pattern for identifying a source telephone;
• generating a reference spreading code using a random number generator;
• encoding the data identification pattern into an identification signal using the spreading code and a spread spectrum modulator, thereby generating a modulated identification signal;
• combining the modulated identification signal with an audio signal of a microphone output of a telephone to form a composite telephone signal, the modulated identification signal being imperceptible to a human listener of the composite telephone signal;
• and
• transmitting the composite telephone signal across a telephonic connection.

A method for identifying a source of a telephone signal received by a remote telephone, the method comprising:

• receiving a composite telephone signal from a source telephone at a remote location, the composite telephone signal comprising an audio signal representative of a telephone conversation and a modulated identification signal, the modulated identification signal having identification data that was embedded therein using a reference spreading code;
• extracting the modulated identification signal;
• and
• analyzing the extracted modulated identification signal to determine if the identification signal contains data that matches at least one of a predetermined set of restricted data signals.

A three way call detection system for detecting the addition of a third party having a third phone to an pre-existing telephonic connection between a first party having a first phone and a second party having a second phone, said system comprising:

• an ID generator for generating identification data;
• a spread spectrum modulator for imposing the identification data onto a carrier signal, said modulator outputting an identification signal having frequency components that are capable of being transmitted via a telephonic connection;
• a signal combiner for adding the identification signal to an output from a microphone of the first phone, thereby producing a combined output signal, said identification signal being added at a level that is imperceptible to a human ear that hears the combined output signal;
• a signal receiver coupled to a third phone, for receiving the combined output signal after transmission across a telephonic connection from the first phone to the third phone;
• a spread spectrum demodulator for demodulating the identification signal to extract the identification data;
• and
• a processor to analyze the identification data.

A detection system for detecting a telephonic connection between a first phone and a second phone, said system comprising:

• an ID generator for generating identification data;
• a spread spectrum modulator for imposing the identification data onto a carrier signal, said modulator outputting an identification signal having frequency components that are capable of being transmitted via a telephonic connection;
• a signal combiner for adding the identification signal to an output from a microphone of a first phone, thereby producing a combined output signal, said identification signal being added at a level that is imperceptible to a human ear that hears the combined output signal;
• a signal receiver for receiving the combined output signal after transmission across a telephonic connection;
• a spread spectrum demodulator for demodulating the identification signal to extract the identification data;
• and
• a processor to analyze the identification data.