Multiparty line adapter with privacy feature controlled by reversal of line polarity at a central power source
First Claim
1. A multiparty line adaptor circuit for enabling a telephone subset to share a single subscriber line from a local or central office with one or more other subscriber subsets, each of said subsets having a similar multiparty line adaptor circuit associated therewith, each of said multiparty line adaptor circuits comprising:
- means for detecting the flow of current in subscriber tip and ring lines when the subscriber goes off-hook;
means for detecting a polarity reversal on said tip and ring lines initiated by said flow of current;
signalling means enabled in response to said polarity reversal on said tip and ring lines for generating and coupling a unique identification signal to said tip and ring lines;
means for generating a signal and coupling said signal to said single subscriber line for enabling all of said multiparty line adaptor circuits sharing said subscriber line in response to said polarity reversal;
means for generating a signal and coupling said signal to said single subscriber line for disabling all said multiparty line adapter circuits in response to said polarity reversal;
signalling receiver means responsive to an interrogate signal to cause said multiparty line adaptor circuit to transmit a unique identification signal to the said subscriber line;
means responsive to said unique identification signal to enable said multiparty line adaptor circuit such that ringing current can be received from said subscriber line at said enabled multiparty line adaptor circuit, and such that none of said disabled multiparty line adaptor circuits receives said ringing current; and
means for receiving said identification signals such that only the calling subscriber and the uniquely identified called subscriber are coupled to the subscriber line, and such that all other subscribers on said multiparty line are disabled and uncoupled thereby maintaining privacy of communication on said multiparty line between said calling and called subscriber.
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Accused Products
Abstract
A circuit for adapting a telephone subscriber line to operate as a multiparty line is described wherein a plurality of conventional single line subscriber subsets are provided telephone service on the subscriber line such that each subscriber has privacy at all stages of call progress. In accordance with another feature of the present invention, frequency selective ringing is not required to prevent ringing from occuring at other subscriber subsets on the multiparty line when a party is called. The circuit of the present invention controls the switching of battery polarity at the central office to connect and disconnect subscribers from the line. The invention further provides automatic telephone number identification when calls are initiated by varying a unique identity tone for billing purposes. The invention also uniquely provides for user transparent reverting calling such that no special dialing procedure is required to make reverting calls and complete privacy is maintained, even on reverting calls.
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Citations
21 Claims
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1. A multiparty line adaptor circuit for enabling a telephone subset to share a single subscriber line from a local or central office with one or more other subscriber subsets, each of said subsets having a similar multiparty line adaptor circuit associated therewith, each of said multiparty line adaptor circuits comprising:
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means for detecting the flow of current in subscriber tip and ring lines when the subscriber goes off-hook; means for detecting a polarity reversal on said tip and ring lines initiated by said flow of current; signalling means enabled in response to said polarity reversal on said tip and ring lines for generating and coupling a unique identification signal to said tip and ring lines; means for generating a signal and coupling said signal to said single subscriber line for enabling all of said multiparty line adaptor circuits sharing said subscriber line in response to said polarity reversal; means for generating a signal and coupling said signal to said single subscriber line for disabling all said multiparty line adapter circuits in response to said polarity reversal; signalling receiver means responsive to an interrogate signal to cause said multiparty line adaptor circuit to transmit a unique identification signal to the said subscriber line; means responsive to said unique identification signal to enable said multiparty line adaptor circuit such that ringing current can be received from said subscriber line at said enabled multiparty line adaptor circuit, and such that none of said disabled multiparty line adaptor circuits receives said ringing current; and means for receiving said identification signals such that only the calling subscriber and the uniquely identified called subscriber are coupled to the subscriber line, and such that all other subscribers on said multiparty line are disabled and uncoupled thereby maintaining privacy of communication on said multiparty line between said calling and called subscriber. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. In a shared subscriber line arrangement, a multiparty line adaptor circuit interposed between a subscriber subset and a central or local telephone exchange for enabling a plurality of subscribers to share a telephone subscriber line such that privacy is maintained at all call stages between the subscribers sharing the line, said circuit comprising:
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line interface means coupled to the subscriber tip and ring lines for providing a transmission path from the shared subscriber line selectively either directly to the subscriber subset or to a circuit path through said multiparty line adaptor circuit; signalling receiver means coupled to said line interface means for receiving subscriber identity signals from said subscriber line and for generating a digital logic code indicative of receipt of a particular identity signal, said code being coupled to a control means for interpretation by said control means; signal transmitter means coupled to said signalling receiver means responsive to the interpretation of said code by said control means for generating and transmitting a unique identity signal indicative of the identity of a subscriber; and control means for decoding said logic signal from said signalling receiver to generate a plurality of commands for selective enabling and disabling of said multiparty line adaptor circuit such that only calling and called parties have access to said subscriber line while a call is in progress. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. In a telephone communication system wherein a plurality of multiparty lines each having a plurality of individual subscribers sharing each subscriber line communicate with a central exchange through a multiparty line adaptor circuit, a method of implementing a reverting call comprising the steps of:
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STEP 1--detection at the central office of a calling subscriber going off-hook. STEP 2--performing a battery voltage reversal at the central office which disconnects all subscribers from the line and enables all multiparty line adaptor circuits; STEP 3--transmitting an interrogation signal from the central office to enable signal transmitters of all multiparty line adaptor circuits; STEP 4--transmission from the calling subscriber'"'"'s multiparty line adaptor circuits of an identification signal to the central office for enabling transmission from the calling subscriber to the central office; STEP 5--returning to normal the battery polarity at the central office to connect the calling subscriber to the subscriber line while maintaining all other subscribers in a disconnected condition from the subscriber line such that the calling subscriber can dial a called subscriber. The calling subscriber dials a called subscriber; STEP 6--the central office recognizes the called subscriber to be on the calling subscriber line; STEP 7--performance of a battery polarity reversal at the central office; STEP 8--transmission of a dual tone multifrequency identification signal from the central office to the called subscriber, to establish a communication path between the central office and the called subscriber. - View Dependent Claims (20, 21)
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Specification