Phone line LAN
First Claim
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1. A method of enabling a data processing system to communicate with a second data processing system, comprising:
- connecting a modem in the data processing system to a telephone conductor;
detecting an existing voltage in the telephone conductor indicating that no communications device connected to the telephone conductor is off-hook; and
configuring the modem to transmit and receive signals on the telephone conductor by adding the signals to the existing voltage, the signals comprising a maximum voltage level which is below a predetermined threshold less than or equal to a difference between the existing voltage and a voltage indicating that a communications device connected to the telephone conductor is off-hook.
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Accused Products
Abstract
Existing modems and phone lines are employed to allow two or more data processing systems to communicate. The data processing systems communicate utilizing weak signals on top of existing phone line voltage levels. The signals are sufficiently small so as not to be interpreted as a receiver being lifted off hook. The weak signals may automatically adapt to changes in the phone line voltage due to a receiver be lifted off hook or an incoming call being signaled. At a sufficiently high frequency, the data processing systems may communicate while the phone lines are being simultaneously employed for conversation.
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Citations
20 Claims
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1. A method of enabling a data processing system to communicate with a second data processing system, comprising:
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connecting a modem in the data processing system to a telephone conductor; detecting an existing voltage in the telephone conductor indicating that no communications device connected to the telephone conductor is off-hook; and configuring the modem to transmit and receive signals on the telephone conductor by adding the signals to the existing voltage, the signals comprising a maximum voltage level which is below a predetermined threshold less than or equal to a difference between the existing voltage and a voltage indicating that a communications device connected to the telephone conductor is off-hook. - View Dependent Claims (2, 3, 4)
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5. An apparatus for enabling a data processing system to communicate with a second data processing system, comprising:
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connection means for connecting a modem in the data processing system to a telephone conductor; detection means for detecting an existing voltage in the telephone conductor indicating that no communications device connected to the telephone conductor is off-hook; and configuration means for configuring the modem to transmit and receive signals on the telephone conductor by adding the signals to the existing voltage, the signals comprising a maximum voltage level which is below a predetermined threshold less than or equal to a difference between the existing voltage and a voltage indicating that a communications device connected to the telephone conductor is off-hook. - View Dependent Claims (6, 7, 8)
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9. A method, in a data processing system, of communicating with a second data processing system, comprising:
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connecting a modem in the data processing system to a telephone conductor; detecting an existing voltage in the telephone conductor; and transmitting and receiving signals on the telephone conductor by adding the signals to the existing voltage, the signals comprising a maximum voltage level which is below a predetermined threshold less than or equal to a difference between the existing voltage and a voltage indicating that a communications device connected to the telephone conductor is off-hook. - View Dependent Claims (10, 11)
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12. An apparatus, in a data processing system, for communicating with a second data processing system, comprising:
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connection means for connecting a modem in the data processing system to a telephone conductor coupling a local exchange to at least one communications device; detection means for detecting an existing voltage in the telephone conductor indicating that no communications device connected to the telephone conductor is off-hook; and signaling means for transmitting and receiving signals on the telephone conductor by adding the signals to the existing voltage, the signals comprising a maximum voltage level which is below a predetermined threshold less than or equal to a difference between the existing voltage and a voltage indicating that a communications device connected to the telephone conductor is off-hook. - View Dependent Claims (13, 14)
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15. A communications adapter for a data processing system, comprising:
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a modem insertable into the data processing system, the modem, when inserted into the data processing system and connected to a telephone conductor coupled to a local exchange; detecting an existing voltage in the telephone conductor indicating that no communications device connected to the telephone conductor is off-hook; and selectively transmitting and receiving signals on the telephone conductor by adding the signals to the existing voltage without allowing a total voltage within the telephone conductor to drop below a threshold voltage interpreted by the local exchange as a communications device being lifted off-hook, the signals comprising a maximum voltage level which is below a predetermined threshold. - View Dependent Claims (16)
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17. A computer program product for use with a data processing system, comprising:
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a computer usable medium; first instructions on the computer usable medium for connecting a modem in the data processing system to a telephone conductor coupled to a local exchange; second instructions on the computer usable medium for detecting an existing voltage in the telephone conductor indicating that no communications device connected to the telephone conductor is off-hook; and third instructions on the computer usable medium for transmitting and receiving signals on the telephone conductor, the signals comprising a maximum voltage level which is below a predetermined threshold, the signals transmitted and received by adding the signals to the existing voltage without allowing a total voltage within the telephone conductor to drop below a threshold voltage interpreted by the local exchange as a communications device being lifted off-hook, wherein the data processing system is equipped to communicate over existing telephone lines. - View Dependent Claims (18, 19, 20)
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Specification