Abstract: A telephone switching network including a remote line switch that couples digital voice signals from a plurality of subscriber lines onto a lesser number of communications links connected to a central office. The remote line switch also includes an intra-nodal switch that switches telephone calls between subscriber lines connected thereto, so that the digital voice signals for the calls need not be transmitted to the central office for switching. The line switch, on receiving a request from the central office for a termination connection to a called line, determines whether both the calling and called lines are connected to it. If they are, and if the line's classes of service as supplied by the central office permit, the line switch establishes a path through its intra-nodal switch to switch the call.

Abstract: A digital tone signal generator for generating digital tone words of selected frequencies and selected cadences in a predetermined number of sequential time slots for use by a telephony system. The generator stores signals representative of each of the frequencies and, in response to a timing signal from the telephony system, generates update signals representative of the amplitudes of the tones at the time the timing signal is received. The cadence is applied to the amplitude signals to obtain the output digital tone word.

Abstract: A line switch including a concentrator arrangement for coupling telephone calls between a plurality of subscriber lines and a plurality of port group highways to a central office switching network in a telephony system. The analog voice signals are first digitized and multiplexed into time slot channels on line group highways for transfer to the concentrator arrangement. The concentrator arrangement couples the digitized voice information signals between time slot channels on any of the line group highways and any of the port group highways. The line switch includes control circuitry that selects the time slot channel, line group highway and port group highway to couple the digitized voice information signals between the subscriber line and the central office matrix switch through the concentrator.

Abstract: A telephone switching system for telephone lines in a telephone network that carry voice and associated supervisory information signals. The voice signals are received through one of a plurality of ports under the control of a port event processor and are transferred through a switching arrangement, under the control of a call processor, and transmitted through a port again under the control of the port event processor. The received supervisory information is stored in a port data store memory, which also stores call state and command information. The port event processor retrieves the stored supervisory information and commands from the port data store memory, and processes the supervisory information in response to the commands in at least two functional units, and returns processed information for storage in the port data store memory.

Abstract: A telephony switching system for interconnecting a plurality of telephone lines. A port storage circuit dedicates an area to each telephone line for storing status information including supervisory information and dial digit information for the corresponding telephone.A port event processor monitors incoming supervisory information from each port means connected to each telephone line to update the corresponding information in each area of the port storage circuit. Upon the occurrence of predetermined events, such as the receipt of all the digits in a telephone number, the port event processor produces an event code that is also stored in the port storage area. A call processor scans all the port storage areas to establish, for each port means, a progression of call states in response to the event information and other information in the port storage circuit and to update control information in the corresponding area.

Abstract: A line circuit for connecting a subscriber line to a telephony system that avoids the use of electro-mechanical elements such as relays. A bridge circuit includes a bilateral current gate in each of the tip and ring lines that can couple or inhibit signals from passing between the subscribed lines and the system. When the bilateral current gates are in an inhibit mode, an on-hook current source energizes the tip and ring lines. A detector senses when the subscriber goes off-hook, and also the dial pulses. After the current gate goes into a coupling mode, the on-hook current source and detector are electrically inactive, and an off-hook current source thereafter provides current to the tip and ring conductors.

Abstract: A common control for a community office (C.O.) switching system includes two interactive processors. A call control processor comprises the uppermost element in the control hierarchy and is a stored program processor that controls call progression, marks paths through a matrix switch network, and performs other functions. A port event processor constructed of "combinatorial logic" is sequentially coupled to every port equipment position connected thereto over a four millisecond scan cycle. Interaction between the call control processor and the port event processor is effected through a port data store, which provides an individual port data file per port equipment position. The port event processor also includes timers that respond to call timing information that can be stored in a port data field for controlling the processing of certain signals from the corresponding port equipment position.

Abstract: A ring trip circuit adapted for use in a community office switching system that includes a call control processor and a port event processor. The call control processor and port event processor interact through a port storage unit that contains information corresponding to each telephone line connected to the switching system. The switching system also includes a ringing generator for transmitting ringing signals onto a telephone line to a called party. Windings for a common bridge relay connect in circuit with each telephone line and diodes shunt the windings so the relay responds only to signals of one polarity. The contacts of the common bridge relay, therefore, reflect the duty cycle of the signal through the common bridge relay and this duty cycle varies when the called party goes off-hook during a ringing burst. The common bridge relay produces a supervisory signal that is sampled and transferred, for each telephone line, to a corresponding port storage area.

Abstract: A central office telephone switching system including two interactive processors, including a call control processor that controls calls by establishing sequences of call progression states, and a port event processor that controls the ports and transmits and receives supervisory information to and from the ports. The port event processor and call control processor communicate through a port data store. The port event processor transfers the received supervisory information to the port data store, for use by the call control processor. The port event processor includes a digital filter that periodically time-samples the received supervisory information and determines the proper state of the received supervisory signal based on the states of the majority of the received sample signals.

Abstract: A telephony network with a digital central office and one or more remotely located digital satellite units. Each digital satellite unit connects to a number of remote subscriber lines and monitors these lines to establish communications through interconnecting spans and a digital satellite interface at the digital central office. The digital satellite interface also connects to port group highways in the digital central switch, to call processors in the digital central switch, and to a maintenance processor in the digital central switch. An automatic test circuit communicates with the interface, and each remote digital satellite unit contains complementary testing circuitry. A test call is made to test the system by activating a test access relay at the remote digital satellite unit and producing a call to the automatic test circuit. The automatic test circuit then generates a tone that is carried as voice data to the remote digital satellite unit test circuit.

Abstract: A telephony network with a digital central office and one or more remotely located digital satellite units. Each digital satellite unit connects to a number of remote subscriber lines and monitors these lines to establish communications through interconnecting spans and a digital satellite interface at the digital central office. The digital satellite interface includes a programmed controller that communicates with the remote digital satellite units connected to it, with call processing equipment in the digital central office and with maintenance processing equipment in the digital central office. Supervisory information and voice data information, in digital form, pass through span equipment that interconnects port group highways in the digital central office and the interconnecting spans. The span equipment strips messages from and inserts messages into signalling time slots on the interconnecting span.

Abstract: A telephony network with a digital central office and a one or more remotely located digital satellite units. Each digital satellite unit connects to a number of remote subscriber lines and monitors these lines to establish communications through interconnecting spans and a digital satellite interface at the digital central office. The digital satellite interface includes a programmed controller that communicates with the remote digital satellite units connected to it, with call processing equipment in the digital central office and with maintenance processing equipment in the digital central office. Communications with the maintenance processor are in the form of messages having a header byte and a byte indicating the length of the message. During network initialization and various recovery operations, the programs and/or the data base can be transferred from the maintenance processor to each digital satellite interface through the use of these messages.

Abstract: A community office switching system includes a three-level hierarchy of distributed processors operating in parallel with one another to control the operation of a central office matrix switch network interconnecting 1,920 ports. At the highest level, a stored-program call control processor controls call progression, establishing paths through the matrix switch network. At the second level, a series of special-purpose, stored-program, port control processors each service 960 ports, sensing and transmitting supervisory signals and communicating the occurrence of significant port events to the call control processor. Each port event control processor dedicates approximately 32 microseconds out of every 32 milliseconds to each of the 960 ports in time-multiplexed fashion, and hence no port can ever be locked out at the port-control-processor level. One from a series of stored programs is executed to service each port precisely one every 32 milliseconds.

Abstract: A telephony system with automatic test calling. Test access circuitry connected to port circuits enables the test call circuit to select actual ports for a test call and monitor the test call signals. Test calls are initiated either on a periodic basis on in resonse to a fault condition. Any portion of the telephony system therefore can be used in a test call.

Abstract: A private telephone network that includes multifunction telephones. Multifunction telephones are connected to common equipment by a voice signal path and a data signal path. Supervisory information passes over the data signal path in the form of polled messages that are sent from the common equipment to the telephone. Sense information is received by the common equipment from the telephone. The transmission is by frequency modulation, such as frequency-shift-keying modulation, techniques. At the multifunction telephone, a programmed microcomputer contains three blocks of instructions for enabling the microcomputer to perform background operations, to respond to the initial receipt of a message, and to thereafter transmit and decode the message. Further, in response to the decoding block of instructions, that are provided on a fixed time basis, the microcomputer is able to transmit frequency-shift-keyed signals without the need for a separate frequency-shift-keyed transmitter.

Abstract: An electronic telephone employing transmit and receive solid-state amplifiers having sufficiently low DC resistance to be biased by a DC signal over a pair of conductors with substantially less than four volts and having sufficiently high AC impedance for transmitting AC communication signals over and receiving AC communications from that pair of conductors. The amplifiers are directly coupled to the conductors, and the amplifiers include a transmitter section comprising a microphone and first solid state amplifier coupling the microphone to the pair of conductors, and a receiver section comprising a speaker and a solid state amplifier coupling the speaker to the pair of conductors. A shunt circuit is connected across the pair of conductors to adjust impedance characteristics of the telephone responsive to the available DC bias.

Abstract: A remote unit contains function circuits to be controlled in response to control data from a central location and function circuits to generate information for transfer to the central location. The control data is transferred between the remote unit and the central location as frequency-shift-keyed signals. In the remote unit, a programmed microcomputer contains three blocks of instructions for enabling the microcomputer to perform background operations, to respond to the initial receipt of a message, and to thereafter transmit and decode the message. Further, in response to the decoding block of instructions, that are provided on a fixed time basis, the microcomputer is able to transmit frequency-shift-keyed signals without the need for a separate frequency-shift-keyed transmitter.Table of ContentsCross References to Related Patent ApplicationsBackground of the InventionSummaryBrief Description of the DrawingsDescription of an Illustrative EmbodimentA. General DescriptionB. Specific Description1.

Abstract: A private telephone network that includes multifunction telephones. Multifunction telephones are connected to common equipment by a voice signal path and a data signal path. Supervisory information passes over the data signal path in the form of polled messages that are sent from the common equipment to the telephone. Sense information is received by the common equipment from the telephone. The transmission is by frequency modulation, such as frequency-shift-keying modulation, techniques. At the multifunction telephone, a programmed microcomputer contains three blocks of instructions for enabling the microcomputer to perform background operations, to respond to the initial receipt of a message, and to thereafter transmit and decode the message. Further, in response to the decoding block of instructions, that are provided on a fixed time basis, the microcomputer is able to transmit frequency-shift-keyed signals without the need for a separate frequency-shift-keyed transmitter.