Telephone system with multiple extension telephones
First Claim
1. A method for communicating between a plurality of telephones over an extension line connected to an outside telephone line, each of the telephones having a selectable-frequency modulator and demodulator, each of the telephones having an on-hook state and an off-hook state, the method comprising:
- detecting a signal on said extension line;
determining whether internal communication is present;
selecting a carrier frequency for transmission receiving an indication of a called extension unit;
sending, from a first telephone, a first signal indicating an extension call, indicating a first carrier frequency for transmission by said first telephone, and indicating the called extension unit;
receiving, at a second telephone, said first signal;
transmitting, from said second telephone, following said step of sending, a second signal indicating an on-hook condition of said second telephone;
transmitting, from said second telephone, a third signal, after entering an off-hook state, indicating said off-hook state and indicating a second carrier frequency for transmission by said second telephone;
selecting, at said second telephone, said first frequency for demodulation and said second frequency for modulation; and
selecting, at said first telephone, said second frequency for demodulation and said first frequency for modulation.
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Accused Products
Abstract
An improved telephone system in which a plurality of telephone units connected to a common telephone line is directly connected to an outside telephone line. Each telephone unit contains complete capability for making outside calls, for making extension calls, and for the automatic exchange control of the use of the common telephone line. This telephone system provides functions, including making multiple simultaneous calls on a single telephone line without requiring separate exchange equipment, additional extension or signal lines, or any sacrifice in signal quality. Furthermore, the telephone units in this system can be connected to more than one outside telephone line to expand the system capacity.
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Citations
27 Claims
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1. A method for communicating between a plurality of telephones over an extension line connected to an outside telephone line, each of the telephones having a selectable-frequency modulator and demodulator, each of the telephones having an on-hook state and an off-hook state, the method comprising:
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detecting a signal on said extension line; determining whether internal communication is present; selecting a carrier frequency for transmission receiving an indication of a called extension unit; sending, from a first telephone, a first signal indicating an extension call, indicating a first carrier frequency for transmission by said first telephone, and indicating the called extension unit; receiving, at a second telephone, said first signal; transmitting, from said second telephone, following said step of sending, a second signal indicating an on-hook condition of said second telephone; transmitting, from said second telephone, a third signal, after entering an off-hook state, indicating said off-hook state and indicating a second carrier frequency for transmission by said second telephone; selecting, at said second telephone, said first frequency for demodulation and said second frequency for modulation; and selecting, at said first telephone, said second frequency for demodulation and said first frequency for modulation. - View Dependent Claims (2, 3, 4)
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5. A telephone extension system for connection to an outside telephone line comprising:
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at least first and second telephones; at least a first telephone extension line directly connected to said outside line and extending between at least said first and second telephones; means for connecting said first telephone to said extension line to establish a first communication at a first average signal level using said outside line; and means for connecting said second telephone to said first extension line to permit a second communication, said second communication occurring without using said outside telephone line, means for limiting said second communication to a maximum average signal level less than said first average signal level to permit said second communication to occur simultaneously with said first communication substantially without interference with said first communication. - View Dependent Claims (6, 7, 8, 9)
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10. A telephone extension system comprising:
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at least a first telephone extension line operably connected to said outside line; a plurality of telephones operably connected to said first extension line; means, in each of said telephones, for selectable connection to said first extension line to establish a first communication at a first average signal level using said outside telephone line; and multiple extension call means, in each of said telephones, for establishing and executing multiple extension calls over said first telephone extension line concurrently with said first communication said multiple extension calls occurring at a maximum average signal level less than said first average signal level. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A telephone extension system for connection to an outside telephone line comprising:
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at least first and second telephone extension lines; first means for connecting each of said first and second telephone extension lines to at least one outside telephone line; a plurality of telephones, each operably connectable to said first and second telephone extension lines, each of said plurality of telephones having speech signal transmitting and receiving means; second means for transmitting and receiving outside call signals on one of said first and second extension lines for selectably providing communication over said outside line; third means for transmitting and receiving, on one of said first and second extension lines, a first carrier signal at a selectable frequency, said carrier signal modulatable with a second signal; fourth means for selectably connecting said speech signal transmitting and receiving means to one of said means for transmitting and receiving outside call signals and said means for transmitting and receiving a carrier signal; fifth means for selecting a frequency for said carrier signal; sixth means for selecting said first or said second telephone extension line for said transmission and reception of a carrier signal; seventh means for selecting said first or second extension line for said transmitting and receiving of outside call signals; and eighth means for modulating a second carrier signal with a command signal. - View Dependent Claims (25, 26)
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27. A telephone for connection to a telephone extension line comprising:
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a handset for receiving and broadcasting sound; a speech network for transmitting and receiving signals to and from said handset and for transmitting and receiving outside line signals; carrier modulator/demodulator circuit for modulating a selectable-frequency transmission carrier with a signal from said handset and for demodulating a selectable-frequency reception carrier to provide a signal to said handset; a controllable switch for selectably connecting said handset to one of said speech network and said modulator/demodulator circuit; a plurality of keys for entering operational commands and data; a command signal demodulator for receiving a remote command signal on said extension line and demodulating said remote command signal to provide a remote command; a command signal modulator for receiving a command signal and modulating a carrier signal in response to said command signal; and a processor for a) receiving said input commands and data; b) controlling said means for selectably connecting said handset; c) selecting a frequency for said selectable-frequency transmission carrier; d) selecting a frequency for said selectable-frequency reception carrier; e) receiving a remote command from said command signal demodulator; f) receiving a hook status signal; and g) issuing a command signal to said command signal modulator in response to at least one of said input commands, said remote command, and said hook status signal, said command signal indicating both a first carrier frequency and a called extension unit.
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Specification