Abstract: A method, system, and computer-readable medium for calculating a minimum echo path delay are provided. An accurate calculation of a minimum echo path delay is made based on characteristics of the echo path. The minimum echo path delay calculation may be periodically repeated thus providing for dynamic calculation of the minimum echo path delay in a manner that accounts for variations in echo path characteristics. The minimum echo path delay may be calculated based on discrete processing latencies identified in the echo path, by a network round trip delay, or by modeling an acoustic echo of an in-band audio signal, performing a frequency analysis thereon to calculate a spectrum signature of the modeled acoustic echo, and monitoring a send path for a match with the modeled acoustic echo after applying an instance of the in-band audio signal into the echo path.

Abstract: Apparatus to permit recognition of a G.165 sampled tone to allow for disabling an echo canceller determines a phase change in the sampled tone. The apparatus comprises a FIFO buffer which receives an input sampled tone and temporarily stores samples from the input sampled tone on a FIFO basis presenting a delayed sampled tone to an adaptive filter core. The core is also input by the input sampled tone. The adaptive filter core introduces a variable delay to the delayed sampled tone such that a phase difference between the input sampled tone and the output of the adaptive filter core iteratively achieves an integer multiple of 2.pi.. The apparatus includes a filter freezer for, after the phase difference achieves a multiple of 2.pi., freezing the adaptive filter such that the adaptive filter the delay in the signal imposed by the adaptive filter is set regardless of any phase difference thereafter arising between the input sampled tone and the output of said adaptive filter core.