Interexchange Trunk Circuit Patents (Class 379/240)
  • Patent number: 8625771
    Abstract: In one embodiment, method can include: receiving an address in a call agent, the address being associated with a call; triggering a trunk group selection algorithm in response to at least a portion of the received address, the trunk group selection algorithm providing a selection result from among a trunk group placeholder and a plurality of trunk groups; and forwarding the call to a trunk group determined by a caller-associated attribute when the selection result comprises the trunk group placeholder.
    Type: Grant
    Filed: November 5, 2012
    Date of Patent: January 7, 2014
    Assignee: Cisco Technology, Inc.
    Inventors: Niels Brunsgaard, Christopher E. Pearce
  • Patent number: 8306210
    Abstract: In one embodiment, method can include: receiving an address in a call agent, the address being associated with a call; triggering a trunk group selection algorithm in response to at least a portion of the received address, the trunk group selection algorithm providing a selection result from among a trunk group placeholder and a plurality of trunk groups; and forwarding the call to a trunk group determined by a caller-associated attribute when the selection result comprises the trunk group placeholder.
    Type: Grant
    Filed: October 3, 2011
    Date of Patent: November 6, 2012
    Assignee: Cisco Technology, Inc.
    Inventors: Niels Brunsgaard, Christopher E. Pearce
  • Publication number: 20120177195
    Abstract: The present invention describes a system and method for communicating voice and data over a packet-switched network that is adapted to coexist and communicate with a legacy PSTN. The system permits packet switching of voice calls and data calls through a data network from and to any of a LEC, a customer facility or a direct IP connection on the data network. The system includes soft switch sites, gateway sites, a data network, a provisioning component, a network event component and a network management component. The system interfaces with customer facilities (e.g., a PBX), carrier facilities (e.g., a LEC) and legacy signaling networks (e.g., SS7) to handle calls between any combination of on-network and off-network callers.
    Type: Application
    Filed: December 30, 2011
    Publication date: July 12, 2012
    Applicant: LEVEL 3 COMMUNICATIONS, LLC
    Inventors: Isaac K. Elliott, Steven P. Higgins, Andrew John Dugan, Jon Peterson, Robert L. Hernandez, Rick D. Steele, Bruce W. Baker, Rich Terpstra, Jonathan S. Mitchell, Jin-Gen Wang, Harold Stearns, Eric Zimmerer, Ray Waibel, Kraig Owen, Shawn M. Lewis
  • Patent number: 8036368
    Abstract: In one embodiment, method can include: receiving an address in a call agent, the address being associated with a call; triggering a trunk group selection algorithm in response to at least a portion of the received address, the trunk group selection algorithm providing a selection result from among a trunk group placeholder and a plurality of trunk groups; and forwarding the call to a trunk group determined by a caller-associated attribute when the selection result comprises the trunk group placeholder.
    Type: Grant
    Filed: October 24, 2007
    Date of Patent: October 11, 2011
    Assignee: Cisco Technology, Inc.
    Inventors: Niels Brunsgaard, Christopher E. Pearce
  • Patent number: 7995736
    Abstract: An embodiment of a method includes generating one or more route plans, each route plan being associated with a service plan, and provisioning the one or more route plans on a core routing engine accessible by a softswitch for routing calls according to the one or more route plans. The one or more route plans may include an on-net route plan and an off-net route plan. An embodiment of a system includes a local route manager (LRM) configured to generate one or more route plans associated with one or more respective service levels that customers can subscribe to. The system may further include an inventory of trunk groups containing a plurality of trunk group identifiers (IDs), wherein trunk group IDs are marked as either on-net or off-net.
    Type: Grant
    Filed: June 14, 2010
    Date of Patent: August 9, 2011
    Assignee: Level 3 Communications, LLC
    Inventors: Matthew K. Davis, Dan Jordan, Greg Gualtieri, Richard Terpstra, Janis Griffin, Murli S. Nair, Susmita G. Saha
  • Patent number: 7995729
    Abstract: An embodiment of a method includes determining a customer service plan identifier from information associated with a received call, determining a route plan associated with the identified customer service plan, and routing the call on a trunk group identified in the determined route plan. The method may further include determining a jurisdiction of the call based on a dialed number identified in the call, determining a local routing number (LRN) associated with the call, and using a portion of the LRN to determine the trunk group. An embodiment of a system includes a switch operable to select a route for routing a call received on an ingress trunk associated with a customer that subscribes to a service plan, wherein the switch is further operable to select the route based on the service plan subscribed to by the customer associated with the ingress trunk.
    Type: Grant
    Filed: December 20, 2010
    Date of Patent: August 9, 2011
    Assignee: Level 3 Communications, LLC
    Inventors: Matthew K. Davis, Dan Jordan, Greg Gualtieri, Richard Terpstra, Janis Griffin, Murli S. Nair, Susmita G. Saha
  • Patent number: 7929676
    Abstract: An embodiment of a method includes determining a customer service plan identifier from information associated with a received call, determining a route plan associated with the identified customer service plan, and routing the call on a trunk group identified in the determined route plan. The method may further include determining a jurisdiction of the call based on a dialed number identified in the call, determining a local routing number (LRN) associated with the call, and using a portion of the LRN to determine the trunk group. An embodiment of a system includes a switch operable to select a route for routing a call received on an ingress trunk associated with a customer that subscribes to a service plan, wherein the switch is further operable to select the route based on the service plan subscribed to by the customer associated with the ingress trunk.
    Type: Grant
    Filed: May 30, 2008
    Date of Patent: April 19, 2011
    Assignee: Level 3 Communications, LLC
    Inventors: Matthew K. Davis, Dan Jordan, Greg Gualtieri, Richard Terpstra, Janis Griffin, Murli S. Nair, Susmita G. Saha
  • Patent number: 7738647
    Abstract: An embodiment of a method includes generating one or more route plans, each route plan being associated with a service plan, and provisioning the one or more route plans on a core routing engine accessible by a softswitch for routing calls according to the one or more route plans. The one or more route plans may include an on-net route plan and an off-net route plan. An embodiment of a system includes a local route manager (LRM) configured to generate one or more route plans associated with one or more respective service levels that customers can subscribe to. The system may further include an inventory of trunk groups containing a plurality of trunk group identifiers (IDs), wherein trunk group IDs are marked as either on-net or off-net.
    Type: Grant
    Filed: May 30, 2008
    Date of Patent: June 15, 2010
    Assignee: Level 3 Communications, LLC
    Inventors: Matthew K. Davis, Dan Jordan, Greg Gualtieri, Richard Terpstra, Janis Griffin, Murli S. Nair, Susmita G. Saha
  • Patent number: 7697671
    Abstract: A method and system of providing data calls to a subscriber having a data network, such as an integrated services digital network (ISDN), connected to a network switch to enable communication with another party at a fixed rate are disclosed. The methodology discovers a data calls system that enables data calls to be placed over trunk lines for communication with a subscriber having an ISDN with a dedicated ISDN line connected to a network edge switch forming a trunk line of the ISDN in communication with a central office. A plurality of base stations are adapted to make and receive data calls using the ISDN over the trunk line. A billing apparatus charges each subscriber a fixed or flat rate per service period for data calls using the trunk line, for the plurality of stations, regardless of the number of calls using the base stations during the service period.
    Type: Grant
    Filed: October 28, 2005
    Date of Patent: April 13, 2010
    Assignee: AT&T Intellectual Property II, L.P.
    Inventor: John Duffy
  • Patent number: 7295603
    Abstract: A method and apparatus implements a Virtual Exchange Reference Impact (VERI) technique to define a pattern to shape the spectrum of a cabinet deployed system to minimize its impact, e.g., FEXT, into an exchange deployed system while achieving effective cabinet system performance, e.g., in terms of data transmission rate. The invention shapes the cabinet system to replicate a self-impact of the exchange system on itself based on the known distance of the cabinet from the exchange. The shaping is required when both exchange and cabinet systems share the same bundle and exhibit overlapped bandwidths. A particular example consists of VDSL deployed from remote cabinet impacting ADSL2/ADSL2+ deployed from the exchange.
    Type: Grant
    Filed: December 13, 2004
    Date of Patent: November 13, 2007
    Assignee: Conexant Systems, Inc.
    Inventors: Patrick Duvaut, Ehud Langberg, Anupama Ramalingam
  • Patent number: 7224686
    Abstract: A communication network includes an SS7 Security Gatekeeper that authenticates and validates network control messages within, transiting, entering and leaving an overlying control fabric such as an SS7 network. The SS7 Security Gatekeeper incorporates several levels of checks to ensure that messages are properly authenticated, valid, and consistent with call progress and system status. In addition to message format, message content is checked to ensure that the originating node has the proper authority to send the message and to invoke the related functions. Predefined sets of templates may be used to check the messages, each set of templates being associated with respective originating point codes and/or calling party addresses. The templates may also be associated with various system states such that messages corresponding to a particular template cause a state transition along a particular edge to a next state node at which another set of templates are defined. Thus, system and call state is maintained.
    Type: Grant
    Filed: January 18, 2001
    Date of Patent: May 29, 2007
    Assignee: Verizon Services Corp.
    Inventors: Arthur Doskow, Harry A. Hetz, Kathleen F. Jarosinski
  • Patent number: 7039175
    Abstract: A PSTN (Public Switching Telephone Network) device includes a Dynamically Configurable Signaling State Machine (DCSSM). The DCSSM can be programmed to recognize multiple signaling templates. The DCSSM can also be programmed to modify existing recognized standardized signaling templates. Programming is accomplished via a configuration interface. Commands are sent to the DCRSSM via the PSTN device's configuration interface. When the trunk controller receives a signal or is required to transmit a signal, the DCSSM executes the directives configured with the programmed signaling templates within a signaling state machine.
    Type: Grant
    Filed: June 2, 2000
    Date of Patent: May 2, 2006
    Assignee: Cisco Technology, Inc.
    Inventors: Richard Foltak, Edward Groenendaal
  • Patent number: 6792098
    Abstract: An inter-network line level adjustment system includes a switch (SW1) and a processing unit (24) for identifying calls between a remote telephone network and a local telephone network. Echo cancellers (20) and/or speech coders (22) collect line level data associated with the identified calls. The processing unit (24) determines statistical properties of the collected line level data. Finally, the processing unit (24) instructs the echo cancellers (20) and/or speech coders (22) to adjust, based on the determined statistical properties, line levels of future calls between the remote telephone network and the local telephone network to a desired line level.
    Type: Grant
    Filed: May 30, 2000
    Date of Patent: September 14, 2004
    Assignee: Telefonaktiebolaget LM Ericsson
    Inventors: Tönu Trump, Anders Roxström
  • Publication number: 20040078827
    Abstract: A DSX system arranged to receive a plurality of high-density chassis is disclosed. The chassis include back planes having rear access IN/OUT fields and rear access cross-connect fields. The rear access IN/OUT fields are electrically connected to termination structures and panels located in respective IN/OUT regions and cross-connect regions. The termination structures of the IN/OUT region includes first and second fanning strips located along edges of termination panels. A double-hinged cover provides access to the termination panels.
    Type: Application
    Filed: October 18, 2002
    Publication date: April 22, 2004
    Inventors: Scott K. Baker, Harvey J. Chouanard
  • Patent number: 6661885
    Abstract: A translation file containing trunk group, trunk level and other translation data is created on a translation input system in response to a circuit provisioning request. An interface between the translation input system and a trunk inventory system transfers the translation file to a translation file directory on a server. The interface logs into the trunk inventory system to generate a translation document to be used by switch technicians to translate trunk groups. Generic views are used rather than conventional structured views to simplify the generation of the translations document. The generic views also reduce the complexity of the software required to implement the interface.
    Type: Grant
    Filed: December 27, 1999
    Date of Patent: December 9, 2003
    Assignee: BellSouth Intellectual Property Corporation
    Inventors: Richard H. McCurdy, Sheila K. Moon, Deborah Baumgardner, James Pugh, Diane C. Stone
  • Patent number: 6603850
    Abstract: A method and system for providing rollover service from a competitive local exchange carrier (CLEC) is disclosed. A routing table is provided which includes call reference values stored within a local bypass system. An incoming call is checked against the call reference values to determine if a call reference value of the incoming call is associated with a grouping of call reference values. The call is connected to a destination associated with a next available call reference value in the grouping using a network control system located within the local bypass system.
    Type: Grant
    Filed: January 11, 2002
    Date of Patent: August 5, 2003
    Assignee: Thomson Licensing S.A.
    Inventors: Thomas Anthony Stahl, John William Richardson
  • Patent number: 6510218
    Abstract: A method for directional distribution of allocation in two-way alternate line bundles which are switched between computer-assisted exchange facilities in voice and data networks. This traffic management method makes it possible to ensure full capability of a two-way alternate line bundle, while on the other hand, when traffic in one direction is temporarily dominant, traffic flow in the other direction is not impaired or displaced. A ratio for dividing the traffic in the outgoing and incoming directions is entered into the exchange facilities for the two-way alternate line bundle connecting them. The division ratio depends on the normal traffic flow in the outgoing and incoming directions. The allocation and direction of allocation of each line of the line bundle are constantly monitored by each of the two exchange facilities. As long as more than one line of the bundle is free, both exchange facilities can access the lines as required by the incoming connections.
    Type: Grant
    Filed: September 29, 1999
    Date of Patent: January 21, 2003
    Assignee: Deutsche Telekom AG
    Inventor: Werner Happel
  • Patent number: 6480596
    Abstract: A direct inward-outward dialing (DIOD) trunk circuit having a DIOD detecting/sending circuit connected to tip and ring terminals connected to a central office line and a primary coil of a transformer, for detecting a polarity of the voltage potential at the tip and ring terminals and the current flowing therethrough to determine reception of one of an incoming and outgoing telephone call, and a switch, controlled by a relay driver responsive to an interface circuit used for interfacing the DIOD trunk circuit with a switching circuit of a private branch exchange (PBX), for enabling the current to flow between the tip and ring terminals through the DIOD detecting/sending circuit via one of a low or high impedance path, wherein the low impedance path is used to establish a speech path between a central office line subscriber and a corresponding extension subscriber of the PBX.
    Type: Grant
    Filed: January 20, 1998
    Date of Patent: November 12, 2002
    Assignee: SamSung Electronics Co., Ltd.
    Inventor: Kyung-Hwa Min
  • Patent number: 6275578
    Abstract: A method of detecting and recovering from an out-of-band signaling failure in a telecommunications network involves the reprogramming of switching centers to utilize existent inband signaling capabilities to temporarily replace the failed out-of-band capability. A processor of an originating switching center recognizes the loss of out-of-band signaling capability, determines impacted trunks and switches to in-band signaling from out-of-band signaling. In an alternative embodiment, the switch may use maintenance data bits of impacted trunks to initiate a call. The terminating switching center is programmed to receive and recognize the change in bit value of the signaling data and initiates well known processes to seize the trunk in memory, check continuity and receive dialed number data, preferably in the form of tones, over the seized trunk. The terminal switching center for the trunk then attempts to complete the call in accordance with the received dialed number data.
    Type: Grant
    Filed: December 23, 1998
    Date of Patent: August 14, 2001
    Assignee: AT&T Corp.
    Inventors: Nicholas D. De Trana, Craig L. DeCaluwe, Hossein Eslambolchi, Patrick H. Fischer, Joseph C. Kohler
  • Patent number: 6148073
    Abstract: An apparatus and method for allocating a data path during a call by establishing a first network call segment associated with an agent and sending a message with routing information across a tandem link using predetermined signaling paths. A second embodiment of the invention comprises a method of allocating a data path during a call wherein the datapath is also a voice path. A third embodiment of the present invention additionally includes apparatus and method for allocating a data path during a call including establishing a two-way connection.
    Type: Grant
    Filed: December 17, 1997
    Date of Patent: November 14, 2000
    Assignee: Northern Telecom Limited
    Inventor: Thomas Helfand
  • Patent number: 5933491
    Abstract: When it is determined, within a local exchange company (LEC) central office of a switched integrated network access (INA) network, that there are insufficient links to handle a terminating call to a competitive LEC (C-LEC) customer, the apparent status of the C-LEC customer is changed the LEC central office, such that, if the terminating call is received by the LEC central office from a C-LEC switch, the C-LEC customer will appear to the C-LEC switch to be unavailable to receive the terminating call, even though the C-LEC customer is in fact not off hook. The present invention avoids the prior-art inefficiencies associated with having time slots for C-LEC customers permanently nailed up by the LEC central office.
    Type: Grant
    Filed: July 1, 1997
    Date of Patent: August 3, 1999
    Assignee: Lucent Technologies Inc.
    Inventors: James H. Miller, Robert C. Purkey
  • Patent number: 5875244
    Abstract: A transmission apparatus for relaying different types of trunk signals, including a central processing unit including a reception counter processor which is inserted between a pair of exchanges and enables direct relay of exchange trunk signals (Sxt) and analog trunk signals (Sem) of a pulse ear and mouth (E&M) mode on a radio transmission line by counting the pulse width of the signals (Sem) and determining their type, a transmission counter processor which transmits the pulse E&M signals until the count of the pulse width inherent to the signals Sem corresponding to the signals Sxt is finished, and a logical operation unit which generates the corresponding signals Sxt based on the result of determination of the reception counter processor and drives the transmission counter processor based on the input signals Sxt, whereby it is possible to give an existing digital transmission apparatus handling E&M signals a function corresponding to a conventional higher rank exchange.
    Type: Grant
    Filed: July 3, 1996
    Date of Patent: February 23, 1999
    Assignee: Fujitsu Limited
    Inventor: Takashi Nagato
  • Patent number: 5844981
    Abstract: A method and system of improved routing to WATS completes calls through a wide area telephone service using indirect routing. When a call is placed from a calling telephone station to a called telephone station, a telephone network attempts to route the call from the originating switch, on which the call entered the network, to a local exchange carrier serving the called station. If other routing paths in the network are unavailable or unsuccessful, a network processor recommends a routing from the originating switch to the local exchange carrier through a tandem switch and the WATS line of another telephone network. This capability provides a reduced incidence of blocked calls, such as may result from telecommunications system outages.
    Type: Grant
    Filed: November 27, 1995
    Date of Patent: December 1, 1998
    Assignee: MCI Communications Corporation
    Inventors: Donald Pitchford, Howard McNeil
  • Patent number: 5774538
    Abstract: An exchange service starting system subject to a minimum of processing burdens without limiting the scope of exchange services available to subscribers. A number dialed by a subscriber placing a call is analyzed by a number analyzing unit. The result of analysis is stored into a number analysis result memory. Upon receipt of a service start request signal from the subscriber during the call, a signal analyzing unit references the content of the memory. If the memory is found to contain a predetermined specific number, the signal analyzing unit starts a signal output unit to output the service start request signal to a specific exchange. If the memory content is other than the specific number, the signal analyzing unit starts a service request processing unit so that the exchange in question will offer a locally available exchange service.
    Type: Grant
    Filed: September 26, 1995
    Date of Patent: June 30, 1998
    Assignee: Fujitsu Limited
    Inventor: Hirofumi Onishi
  • Patent number: 5717750
    Abstract: A method for detecting translation data error in a central office switch comprises: receiving a call directed to a ported directory number in a switch; retrieving translation data from the switch memory to connect the call to a customer line; and determining that the call cannot be completed to a customer line served by the switch. Upon determining that the call cannot be connected to a customer line served by the switch, a translation data error (TDE) indicator is set in the switch memory so that the instant call, and all subsequent calls directed to the same ported directory number, are connected to an announcement circuit. An translation data error message is also sent to a central switch maintenance and control center by the switch.
    Type: Grant
    Filed: September 18, 1995
    Date of Patent: February 10, 1998
    Assignee: Lucent Technologies Inc.
    Inventors: William Lowell Adams, Jr., Valerie Y. Boyle, Ronald Bruce Martin, Robert Allen Swanson, Douglas Paul Totel, Robert Mark Yacobi
  • Patent number: 5414763
    Abstract: A telephone switching apparatus includes a line network to which first and second telephones are connected and a hands-free trunk whose input and output terminals are connected to the line network. The line network is controlled such that voices from the first and second telephones are transmitted to the second and first telephones, respectively, through the hands-free trunk. A call transfer apparatus includes an outside-line interface to which first and second outside lines are connected and an adjusting unit for comparing the volumes of voices from the first and second outside lines and adjusting the volumes of the voices in accordance with the results of the comparison. The voices input from the first and second outside lines and adjusted in volume are transmitted to the second and first outside lines, respectively.
    Type: Grant
    Filed: February 25, 1992
    Date of Patent: May 9, 1995
    Assignee: Canon Kabushiki Kaisha
    Inventor: Osamu Hirata
  • Patent number: 5151935
    Abstract: A programmable universal signaling circuit for use in a universal channeling unit of a telephone network. The programmable universal signaling circuit uses a line converter and decoder circuit which under control of a microprocessor generates a unique set of configuration signals for configuring the universal signaling circuit into one of a plurality of standard signaling telephone circuits. The universal signaling circuit can be reconfigured either at the location of the universal channel unit or remotely.
    Type: Grant
    Filed: November 2, 1990
    Date of Patent: September 29, 1992
    Assignee: XEL Communications, Inc.
    Inventors: Jimmy D. Slife, David Farrell
  • Patent number: 5018195
    Abstract: In order to extend a new unit to a telecommunication network comprising a plurality of units often distributed geographically and interconnected by means of transmission lines, or adapting the software of the various units, without causing problems with the control communication between the units, the control communication is divided into a number of successive levels, for each level, specifically for the lowest level while a code number belonging to the software of this unit is stored in each unit. Communication between two units at a specific level is only possible if the code numbers match and if at all lower levels communication already takes place.
    Type: Grant
    Filed: September 26, 1989
    Date of Patent: May 21, 1991
    Assignee: U.S. Philips Corporation
    Inventor: Lawrence M. Hall
  • Patent number: 4930153
    Abstract: An interface is described which attaches between the incoming trunk lines from a central office and a PBX system and which monitors the communication between the central office and the PBX to record the signals representative of telephone extension of a called party for later downloading to telephone peripheral equipment attached to the PBX, such as voice mail systems. The interface passively monitors the line during handshake communication between the central office and the PBX and receives the digits of the dialed extension and stores them in memory. The interface then monitors the line for a request to send from the peripheral equipment attached to the PBX. When the request is received, the interface assumes supervision of the telephone line by terminating the line to the central office and the line to the PBX. The interface then downloads the digits of the dialed extension to the telephone peripheral equipment, such as a voice mail system, for identifying the extension to which the message belongs.
    Type: Grant
    Filed: April 7, 1989
    Date of Patent: May 29, 1990
    Assignee: Nicollet Technologies, Inc.
    Inventor: Guenter E. Hagedorn
  • Patent number: 4899379
    Abstract: A circuit for implementing a connection of an operational amplifier, and for achieving the switchable sensitivity of the same, as well as the in-and-out switchable filter elements, which results in a low cost, universally applicable line circuit interconnect circuit.
    Type: Grant
    Filed: June 12, 1989
    Date of Patent: February 6, 1990
    Assignee: Siemens Aktiengesellschaft
    Inventor: Peter Vaclavik
  • Patent number: 4894860
    Abstract: This invention relates to improved trunk interface circuitry for telephone system common equipment, which is used to connect a local customer system to a central office of the telephone company. The improved trunk interface comprises an active two-terminal current sink for limiting the loop current in a non-linear manner, and means for monitoring the voltage across the trunk line which comprises a voltage-to-pulse width converter. The voltage-to-pulse width converter is designed to operate with a microprocessor which measures the time it takes to linearly discharge a capacitor which has been charged to the line voltage.
    Type: Grant
    Filed: June 7, 1988
    Date of Patent: January 16, 1990
    Assignee: TIE/communications, Inc.
    Inventors: Vincent V. Korsky, Rajmund Krzyszczyk, Jin T. Lim
  • Patent number: 4853955
    Abstract: The invention relates to upgrading existing telephone central offices which utilize electromechanical or electronic switching equipment incapable of using the SS7 protocol. In particular, it relates to providing the switching equipment with the capability of controlling the connection, management, and disconnection of telephone circuits using Signaling System Number 7, a national and international standard set of protocols for providing such circuit control and providing and receiving information via the SS7 protocol for enabling enhanced service in the switching equipment.
    Type: Grant
    Filed: April 27, 1988
    Date of Patent: August 1, 1989
    Assignee: Network Access Corporation
    Inventors: David W. Thorn, Rajendra Patel, Gerald Coley, Ashok Trivedi, Girish Patel
  • Patent number: 4815124
    Abstract: An improved DX circuit may be connected to signaling and reference leads of a DX signaling link, without need to balance the internal impedance of the DX circuit against that of the external DX signaling link. The DX circuit senses the magnitude and direction of current flow on the leads, and operates on the principle that when a near end signaling circuit is on-hook, a positive current flow indicates that a far end signaling circuit is off-hook and a current flow of zero indicates that it is on-hook, while if the near end signaling circuit is off-hook, a negative current flow indicates that the far end signaling circuit is on-hook and a current flow of zero indicates that it is off-hook. The arrangement allows the DX circuit to properly function irrespective of the resistive load presented by the DX signaling link.
    Type: Grant
    Filed: June 26, 1987
    Date of Patent: March 21, 1989
    Assignee: Tellabs, Inc.
    Inventors: Blaine T. Bowers, Wayne E. Walters
  • Patent number: 4689816
    Abstract: An interface system having a single detector to detect incoming signalling including ringing, tip ground, forward loop current, and reverse loop current. Relays and bias control are utilized to perform outgoing signalling and for configuring the system to defect the various incoming signalling states with a single detector.
    Type: Grant
    Filed: January 15, 1985
    Date of Patent: August 25, 1987
    Assignee: D.A.V.I.D. Systems, Inc.
    Inventor: Samuel F. Wood
  • Patent number: 4636584
    Abstract: Disclosed is a channel unit for directly interconnecting a toll office multiplex carrier channel line and a terminal unit line such as that of a private branch exchange (PBX) or a telephone station set, thereby eliminating the normal local end office interconnection. In particular, the channel unit interfaces the different signaling protocols of the two lines and generates call progress controls signals such as dial tone and audible ringing which are normally generated by the local end office. The channel unit comprises a converter for each line for converting the electrical interface signals representative of the busy and idle conditions of the line to logic level signals also representative of the busy and idle conditions of the line. A predetermined series of these logic level signals form a control signal that indicates the state in one signaling protocol of a call on the line.
    Type: Grant
    Filed: December 19, 1983
    Date of Patent: January 13, 1987
    Assignee: AT&T Bell Laboratories
    Inventors: Mark S. Binkerd, William C. Sand