DTMF tone detection and suppression with application to computer telephony over packet switched networks
First Claim
Patent Images
1. A method of facilitating telephony communication over a packet-switched network, comprising the steps of:
- detecting signaling tones in an audio stream, blocking the signaling tones detected in the step of detecting from the audio stream in response to the step of detecting, and sending the audio stream over an undependable audio channel in the packet-switched network after the step of blocking the signaling tones.
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Abstract
A method of facilitating telephony communications over a packet-switched network includes detecting signaling tones in an audio stream and blocking them from the stream in response to the detecting. After the blocking, the audio stream is sent over an undependable channel in the packet-switched network. The detected signaling tones can be sent over a dependable channel instead of the undependable audio channel.
33 Citations
37 Claims
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1. A method of facilitating telephony communication over a packet-switched network, comprising the steps of:
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detecting signaling tones in an audio stream, blocking the signaling tones detected in the step of detecting from the audio stream in response to the step of detecting, and sending the audio stream over an undependable audio channel in the packet-switched network after the step of blocking the signaling tones. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 10, 11)
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5. A method of facilitating telephony communication over a packet-switched network, comprising the steps of:
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detecting signaling tones in an audio stream, including a step of low-pass filtering, a step of low band-pass filtering, a step of high band-pass filtering, determining if a result of the step of low-pass filtering is too large, determining if results of the steps of band-pass filtering are too small, and determining if results of the steps of band-pass filtering are too different, blocking the signaling tones detected in the step of detecting from the audio stream in response to the step of detecting, and sending the audio stream over an undependable audio channel in the packet-switched network after the step of blocking the signaling tones.
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12. An audio detection and suppression system for use in connection with packet-switched networks, comprising:
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means for detecting signaling tones in an audio stream, and means for suppressing the signaling tones in the stream detected by the means for detecting before they are sent from an audio output over an undependable audio channel in the packet-switched network. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 22)
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21. An audio detection and suppression system for use in connection with packet-switched networks, comprising:
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means for detecting signaling tones in an audio stream, including a low-pass filter, a low band-pass filter, a high band-pass filter, means for determining if an output of the low-pass filter is too large, means for determining if outputs of the band-pass filters are too small, and means for determining if outputs of the band-pass filters are too different, and means for suppressing the signaling tones in the stream detected by the means for detecting before they are sent from an audio output over an undependable audio channel in the packet-switched network.
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23. A method of facilitating telephony communication over a packet-switched network, the method comprising the steps of:
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passing an audio stream through a system having at least one filter prior to an audio output, detecting a selected audio signal in the audio stream utilizing the at least one filter, and blocking the selected audio signal from passage through the audio output in response to the step of detecting. - View Dependent Claims (24)
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25. The method of detecting a selected signal in a digital signal, comprising:
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decimating the digital signal to obtain a decimated digital signal, applying a statistical test to the decimated digital signal, and determining whether the selected signal is present in the digital signal based on the result of the step of applying. - View Dependent Claims (26, 27, 28, 29)
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30. A system for receiving first audio signals and transmitting second audio signals to a packet-based network, the system comprising:
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an input for receiving the first audio signals;
a band-pass filter arrangement coupled to the input and configured to pass a filtered signal having a frequency associated with a dual-tone, multi-frequency pair; and
a processor coupled to the filter arrangement;
wherein at least one of the filter arrangement and the processor is configured to decimate the filtered signal to produce a filtered, decimated signal; and
wherein the processor is configured to compare characteristics of the filtered, decimated signal to determine whether the filtered, decimated signal is representative of a portion of a dual-tone, multi-frequency signal. - View Dependent Claims (31, 32, 33)
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34. A method for receiving first audio signals and transmitting second audio signals to a packet-based network, the method comprising:
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receiving the first audio signals;
filtering and decimating the first audio signals to pass a filtered, decimated signal having a frequency associated with a dual-tone, multi-frequency pair; and
comparing characteristics of the filtered, decimated signal to determine whether the filtered, decimated signal is representative of a portion of a dual-tone, multi-frequency signal. - View Dependent Claims (35, 36, 37)
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Specification