Method of converging an echo canceller

Claim 1

A method for converging an adaptive echo canceller at the beginning of a telephone call between a calling subscriber and a called subscriber during which the called subscriber will transmit a speech signal to the calling subscriber, said method comprising: (a) establishing a transmission connection through a telephone exchange between a calling subscriber and a called subscriber over a telephone system which includes said telephone exchange, which telephone exchange has an adaptive echo canceller integrated thereinto; (b) at said telephone exchange detecting an off-hook state of the called subscriber, using a call control; (c) in response to said detecting of said off-hook state, outputting an internal command of said telephone interchange to said echo canceller from said call control, for initiating convergence of said echo canceller; and (d) in response to receipt by said echo canceller of said internal command, transmitting a test signal from said echo canceller along said transmission connection towards said calling subscriber, and using reception by said echo canceller of a return of said test signal along an echo path of said transmission connection to said echo canceller to converge said echo canceller before appearance of said speech signal on said transmission connection; and (e) utilizing said echo canceller, as thereby converged, to suppress echo in transmission of said speech signal on said transmission connection.

Claim 2

A method for converging an adaptive echo canceller at the beginning of a telephone call between a calling subscriber and a called subscriber during which the called subscriber will transmit a speech signal to the calling subscriber, said method comprising: (a) establishing a transmission connection through a telephone exchange between a calling subscriber and a called subscriber over a telephone system which includes said telephone exchange, which telephone exchange has an adaptive echo canceller integrated thereinto; (b) at said telephone exchange detecting an off-hook state of the called subscriber, using a call control; (c) in response to said detecting of said off-hook state, outputting an internal command of said telephone interchange to said echo canceller from said call control, for initiating convergence of said echo canceller; and (d) in response to receipt by said echo canceller of said internal command, transmitting a test signal from said echo canceller along said transmission connection towards said calling subscriber, and using reception by said echo canceller of a return of said test signal along an echo path of said transmission connection to said echo canceller to converge said echo canceller before appearance of said speech signal on said transmission connection; and (e) utilizing said echo canceller, as thereby converged, to suppress echo in transmission of said speech signal on said transmission connection.

Claim 5

A method for converging an adaptive echo canceller at the beginning of a telephone call between a calling subscriber and a called subscriber during which the called subscriber will transmit a speech signal to the calling subscriber, said method comprising: (a) establishing a transmission connection through a telephone exchange between a calling subscriber and a called subscriber over a telephone system which includes said telephone exchange, which telephone exchange has an adaptive echo canceller integrated thereinto; (b) transmitting a series of ring-back tones along said transmission connection to said calling subscriber, indicating that an off-hook state does not yet exist in regard to said called subscriber; (c) at said telephone exchange using a call control to cause said echo canceller to transmit a test signal interspersed with said ring-back tones, towards the calling subscriber, for initiating convergence of said echo canceller; (d) using a return of said test signal along an echo path of said transmission connection to said echo canceller to converge said echo canceller before said called subscriber creates an off-hook state; and (e) utilizing said echo canceller, as thereby converged, to suppress echo in transmission of said speech signal on said transmission connection.

Claim 6

A method for converging an adaptive echo canceller at the beginning of a telephone call between a calling subscriber and a called subscriber during which the called subscriber will transmit a speech signal to the calling subscriber, said method comprising: (a) establishing a transmission connection through a telephone exchange between a calling subscriber and a called subscriber over a telephone system which includes said telephone exchange, which telephone exchange has an adaptive echo canceller integrated thereinto; (b) transmitting a series of ring-back tones along said transmission connection to said calling subscriber, indicating that an off-hook state does not yet exist in regard to said called subscriber; (c) at said telephone exchange using a call control to cause said echo canceller to transmit a test signal interspersed with said ring-back tones, towards the calling subscriber, for initiating convergence of said echo canceller; (d) using a return of said test signal along an echo path of said transmission connection to said echo canceller to converge said echo canceller before said called subscriber creates an off-hook state; and (e) utilizing said echo canceller, as thereby converged, to suppress echo in transmission of said speech signal on said transmission connection.