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: Digit analysis within an electronic private automatic branch exchange telephone system is carried out through interconnected sections of digit decoder circuitry. A first portion of the digit decoder effectively processes dialed impulses originating within the PBX system and determines whether or not the call is to be directed to another line within the system, to a trunk or to the attendant. The contents of an ING and ED memory are continuously monitored and modified, where necessary on a time shared basis with the other calls processed by the system. Direct inward dialing and listed directory number analysis is carried out in a second portion of the decoder which also causes the ING and ED memory to be monitored and modified, where necessary for the processing of the digits. For either internally directed or externally directed calls, the sequentially received digits are initially processed in the units position of the memory and appropriate action is taken as the result thereof.

Abstract: A timer circuit receives a multi-bit digital signal representative of a timing code to be incremented. In dependence upon the coded value of the received signal, the code represented by the signal will be incremented at a selected clock rate. The clock rate selected may be chosen to decrease in frequency in a stepwise manner as the code is incremented. As the timing interval increases, the percent resolution of the timing code is maintained substantially constant.

Abstract: A trunk adapter is associated with a common control private automatic branch exchange telephone system for interfacing the system with a central office. Four different types of adapters are associated with the system to effect a ring-down incoming, loop start outgoing trunk connection, a ground start type trunk connection, a two-way dial-to-dial trunk connection, and a two-way E and M signalling interface. To provide a buffer between the ring and tip circuits the adapters employ optical coupler circuits. The adapters are controlled by the common control on a time shared basis and operate independently of the state of the sleeve lead.

Abstract: A circuit for detecting a true seizure condition of a trunk calling bridge relay employs a timer which is incremented every 40 milliseconds as long as a continuous trunk off-hook representative signal is supplied thereto for approximately 300 milliseconds. For momentary changes in the condition of the trunk CB relay the timer will be incremented and decremented so as to effectively filter out momentary trunk calling bridge seizure changes.

Abstract: An electronic private automatic branch exchange may avoid the need for access trunks and information trunks in the operator complex by utilizing a single stage switching matrix to effect connections between line circuits, trunk circuits, and the operator under control of the common control. To accomplish this the operator line circuits are provided and operator loop circuits as line appearances at the inputs of the matrix. In addition, the common control is provided with recognition circuitry for recognizing a request from a line for connection to the operator or a request by the operator for connection to a line and conversion circuitry for converting such requests to a multidigit designation of the operator line circuit or loop circuit to be acted upon by the system in the manner of a connection of a line circuit.

Abstract: An arrangement is disclosed for providing trunk consultation in an electronic private automatic branch exchange which is built around a space divided solid state matrix. The trunk consultation arrangement is enabled by a hookswitch flash from a consulting PABX station connected to an established incoming or outgoing trunk call and directs the trunk junctor associated with that call to place the connected trunk on hold. While the connected trunk junctor is in a held status, the consulting PABX station is forwarded to a local junctor where the consulted trunk party is dialed. A connection between the consulting PABX station and the consulted trunk party is then established via a second trunk junctor. Further circuitry is provided in the trunk consultation arrangement to establish a three-way consultation between the consulting PABX station, the consulted trunk party, and the held trunk party.

Abstract: In an electronic private automatic branch exchange telephone system, busy test is carried out by way of a two step process. Initially, a junctor memory is scanned and the called number is compared with each ING and ED number contained in memory. At the completion of the scan and comparison a check of the calling bridge relay of the called number is made. Associated with the busy test arrangement are camp-on and call-waiting features which may also be carried out during the test.

Abstract: A local transfer arrangement for an electronic private automatic branch exchange having a space divided rectangular solidstate switching matrix is disclosed. The local transfer arrangement is provided with means for sensing a local transfer indication from either a calling station or a called station connected by a local junctor. The transfer indication causes the system to forward the transferring station to a second local junctor and hold the first local junctor. A transferee station is then signaled via the second local junctor of the impending local transfer by the transferring station. Thereafter, an automatic forwarding of the transferee station to the first local junctor is initiated by an on-hook condition of the transferring station to complete the operation. Additional features of the arrangement provide for a return to the original call and release of the connected junctors responsive to an on-hook or hookflash condition of the transferring station.

Abstract: A tie trunk control arrangement is disclosed for providing tie trunk connections in an electronic private automatic branch exchange which is built around a space divided solid state matrix. Each tie trunk has an associated tie trunk junctor dedicated thereto which may be connected to local stations by the PABX system in a manner similar to other trunk junctors. For incoming tie trunk connections an attendant extension or station attendant extension is used for providing connections to other PABX stations and trunk circuits. Common circuitry used for trunk transfer and trunk consultation may be used by the station attendant to extend the tie trunks to the PABX stations and the outgoing trunk junctors. Further circuitry is provided by the tie trunk control arrangement to allow a tie trunk and a central office trunk to be tandemed in the system or to allow two tie trunks to remain tandemed in the system without attendant supervision.

Abstract: An electronic private automatic branch exchange is built around a space divided solid state matrix. One side of the solid matrix provides line appearances which are connected to line circuits, tone receivers, senders and operator loops. The other coordinate side of the matrix provides junctor appearances for connection to an attendant junctor, local junctors and trunk junctors. The solid state switching matrix is a single stage matrix providing direct connection between line appearances and junctor appearances by the closing of a single crosspoint, and connection between lines within the system is effected simply by the interconnection of a pair of crosspoints associated with the respective lines and a selected junctor, thereby providing a greatly decreased switching for establishing a connection through the matrix. The control necessary for effecting such connections is provided with much simpler common control equipment than is utilized in a conventional multistage switching network.

Abstract: In a digital signalling network of the kind in which only data pulses are transmitted among the different stations, and more than one of the stations includes means for producing clock signals, synchronization of the network is achieved by producing at each station, in response to received data pulses, derived clock signals at the same rates as the clock signals produced at each of the other stations. Each station scans all available clock signals, its own and all those derived from the incoming data signals, compares the scanned signals one by one with its own operating rate, and adjusts the rate to conform to the slowest signal. The signals of concern are time-spaced electrical pulses, and rate comparison is accomplished by counting.

Abstract: A circuit is disclosed for providing trunk transfer in an electronic private automatic branch exchange which is built around a space divided solid state matrix. The trunk transfer circuit is enabled by a hookswitch flash from a transferring PABX station connected to an established incoming or outgoing trunk call and directs the trunk junctor associated with that call to place the connected trunk on hold. While the connected trunk junctor is in a held status, the transferring PABX station is forwarded to a local junctor by the trunk transfer circuit and a connection is established from the local junctor to a transferee PABX station. The trunk transfer circuit then completes the transfer by establishing a connection between the held trunk and the transferee PABX station via the held trunk junctor.