| 摘要 |
A system and a method (10) for detecting and identifying call progress tones are disclosed. Signals on a telephone line are sampled and the frequencies having the highest power are identified as signal components. The frequencies and power level for each component and the total signal power are autocorrelated to generate autocorrelation peaks for each of the three components. Signal information (13), such as autocorrelation peaks, duty cycle and pulse repetition interval is compared to a database of call progress tone templates. The call progress tone is identified by matching it to one of the database templates (14).
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