Method and apparatus for detecting the connection status of an extension phone connected to a voice/fax/data modem
First Claim
1. A device for answering a telephone call received along a telephone line having at least one extension line, said device comprising:
- means, connected to the telephone line, for answering an in-coming telephone call received along the telephone line;
means for determining whether the in-coming call contains a data message or a voice message;
means for recording a portion of the voice message in response to a determination that the incoming call contains a voice message;
means for detecting an off-hook condition on said extension line by detecting a change in voltage on said telephone line caused by said extension line being taken off-hook, said means for detecting comprising;
a voltage peak detector having a slowly-varying response for generating a signal representative of an average voltage occurring on said telephone line;
a voltage peak detector having a quickly-varying response for generating a signal representative of a current voltage along said telephone line; and
a voltage comparator having first and second inputs connected to said voltage peak detector having a slowly-varying response and said voltage peak detector having a quickly-varying response for comparing said signals representative of said current voltage and said average voltage and for detecting a difference between said current voltage and said average voltage; and
means, operative in response to the detection of an off-hook condition, for terminating operation of said means for recording the voice message.
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Accused Products
Abstract
A detector circuit is provided for detecting the off-hook status of the extension telephone line. The detector is connected to tip and ring lines of the telephone line for determining a change in the voltage between the tip and ring lines. The detector includes a low pass filter for filtering noise and AC signals. The filtered signals are transmitted through a converter which converts a differential voltage between the signals into an absolute voltage relative to a ground. A pair of voltage peak detectors generate output signals in response to changes in the absolute voltage. A first peak detector provides a quickly varying output signal representing an instantaneous voltage. The second peak detector provides a slowly varying output response representative of an average voltage over a period of time. The average voltage is employed as a reference voltage against which the instantaneous voltage is compared. If a substantial difference between the instantaneous voltage and the average voltage is detected, a logic output signal is generated which indicates that an extension line is off-hook. In one embodiment, the detector circuit is employed as a component of a voice/data/fax modem. The modem responds to the detection of the off-hook extension line by deactivating a voice answering machine cycle. Further method and apparatus embodiments of the invention are described.
84 Citations
18 Claims
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1. A device for answering a telephone call received along a telephone line having at least one extension line, said device comprising:
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means, connected to the telephone line, for answering an in-coming telephone call received along the telephone line; means for determining whether the in-coming call contains a data message or a voice message; means for recording a portion of the voice message in response to a determination that the incoming call contains a voice message; means for detecting an off-hook condition on said extension line by detecting a change in voltage on said telephone line caused by said extension line being taken off-hook, said means for detecting comprising; a voltage peak detector having a slowly-varying response for generating a signal representative of an average voltage occurring on said telephone line; a voltage peak detector having a quickly-varying response for generating a signal representative of a current voltage along said telephone line; and a voltage comparator having first and second inputs connected to said voltage peak detector having a slowly-varying response and said voltage peak detector having a quickly-varying response for comparing said signals representative of said current voltage and said average voltage and for detecting a difference between said current voltage and said average voltage; and means, operative in response to the detection of an off-hook condition, for terminating operation of said means for recording the voice message. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A telephone answering device for answering a telephone call received along a telephone line having at least one extension line, said telephone line including tip and ring lines, said device comprising:
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a memory; voice/data/fax modem means, connected to the telephone line and to said memory, for answering a telephone call received along said telephone line, for determining whether a message received along said telephone line contains a data message or a voice message, for recording said data message in said memory, if said message contains data and for recording a voice message in said memory, if said message is a voice message; means for detecting an off-hook condition on said extension line by detecting a change in voltage on said telephone line caused by said extension line being taken off-hook, said means for detecting comprising; converter means for converting a voltage difference between the tip and ring lines into an absolute voltage signal relative to a ground; first voltage detection means for generating a signal representative of an average voltage said first voltage detection means having a slowly-varying response; second voltage detection means for generating a signal representative of a current voltage, said second voltage detection means having a quickly-varying response; and means for comparing said signals representative of said current voltage and said average voltage and for detecting a difference between said current voltage and said average voltage; and means, operative in response to the detection of an off-hook condition, for terminating operation of said means for recording a voice message, if said input message is voice. - View Dependent Claims (10, 11, 12, 13)
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14. A device for answering a telephone call received along a telephone line having at least one extension line, said device comprising:
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means, connected to the telephone line, for answering an in-coming telephone call received along the telephone line; means for determining whether the in-coming call contains a data message or a voice message; means for recording a portion of the voice message in response to a determination that the incoming call contains a voice message; means for detecting an off-hook condition on said extension line by detecting a change in voltage on said telephone line caused by said extension line being taken off-hook, wherein said means for detecting a change in voltage on said telephone line comprises; a low pass filter means for filtering a differential voltage signal received from said telephone line; voltage conversion means, connected to said low pass filter, for converting a filtered differential voltage signal to an absolute voltage relative to a ground; a voltage peak detector having a slowly-varying response, connected to an output of said voltage conversion means, for generating a signal representative of an average of said absolute voltage; a voltage peak detector having a quickly-varying response, connected to said output of said voltage conversion means, for generating a signal representative of a current voltage value of said absolute voltage; and a voltage comparator having first and second inputs connected to said means for generating a signal representative of an average voltage and said means for generating a signal representative of a current voltage, respectively for comparing said signals representative of said current voltage and said average voltage and for detecting a difference between said current voltage and said average voltage; means, operative in response to the detection of an off-hook condition, for terminating operation of said means for recording the voice message.
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15. A device for answering a telephone call received along a telephone line having at least one extension line, said device comprising:
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a memory; a modem, connected to the telephone line, for answering an in-coming telephone call received along the telephone line, the telephone line including tip and ring lines, said modem determining whether the in-coming call contains a data message or a voice message and recording a voice message in said memory, if the incoming call contains a voice message; and an off-hook detector, operably connected to said telephone line and to said modem, said off-hook detector detecting an off-hook condition on said extension line by detecting a change in voltage on said telephone line caused by said extension line being taken off-hook and transmitting a signal representative of said off-hook condition to said modem, said modem terminating the recording of the voice message in response to the detection of an the off-hook condition on said extension line, wherein said detector comprises; a low pass filter connected to said tip and rings lines; a differential voltage-to-absolute voltage converter, connected to an output of said low mass filter, said converter converting a voltage difference between said filtered tip and ring lines to an absolute voltage relative to a ground; a first voltage peak detector, connected to an output of said differential-to-absolute voltage converter, said first voltage peak detector having slowly-varying response; a second voltage peak detector, connected to an output of said differential-to-absolute voltage converter, said second voltage peak detector having a quickly-varying response; and a comparator, connected to outputs of said first and second voltage peak detectors, said comparator generating a signal if an output signal from said first voltage peak detector differs substantially from an output of said second voltage peak detector. - View Dependent Claims (16, 17)
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18. A method for processing a telephone call received along a telephone line having at least one extension line, said telephone line including tips and ring lines, said method comprising the steps of:
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answering an in-coming telephone call received along the telephone line; determining whether the in-coming call contains a data message or a voice message; recording a portion of the voice message in response to a determination that the incoming call contains a voice message; detecting an off-hook condition on said extension line by detecting a change in voltage on said telephone line caused by said extension line being taken off-hook said detecting step comprising the steps of; converting a voltage difference between the tip and ring lines into an absolute voltage signal relative to a ground; generating a signal representative of an average voltage; generating a signal representative of a current voltage; and comparing said signals representative of said current voltage and said average voltage and detecting a difference between said current voltage and said average voltage; and terminating the recording of the voice message in response to the detection of the off-hook condition.
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Specification