Patent ID: 6266398
Filing Date: 2001-07-24
Classification: G10L

Abstract:
A telephone line interface card comprising:means for coupling the line card to at least one telephone line allowing the line card to receive a line signal indicative of user speech;means for transmitting prompts to a user on the at least one telephone line; andmeans for detecting the presence of user speech on the at least one telephone line concurrent with the transmission of a prompt, the detecting means comprising:means for measuring a prompt residue resulting from imperfect cancellation of the prompt during at least a portion of a first interval in which said prompt residue is present and said speech is absent;means for forming, over a subsequent interval, a prompt residue model based on said prompt and the measured residue; andmeans for providing an indication of the presence of speech on the at least one telephone line when the signal on said at least one line differs from said prompt residue model by a threshold.