Abstract: An improved call forwarding arrangement where forwarded calls receive different terminating treatment from non-forwarded calls, for example providing a readily detectable, distinctive alerting signal for forwarded calls or completing only forwarded calls to a station and denying or forwarding other calls without requiring any customer involvement. The arrangement provides an improved call forwarding service for customers with advanced station display capabilities and, in addition, allows selective answering of only forwarded calls by customers that have conventional, analog station equipment. Both switch-based and station-based implements are disclosed.

Abstract: A detachably attachable protection device for use with a circuit routed to a DSX panel or the like in a telephone switching station includes a fixed plate having apertures for visual access to a light associated with the circuit, an aperture for access to a monitor jack and a pivotable plate connected to the fixed plate for selectively providing access to jacks for rerouting the circuit. The lift tab may be incorporated to assist in positioning the pivotable plate. In a variant protection device, a plurality of pivotable plates secured to a common fixed plate may be employed to individually protect all circuits routed to a DSX panel.

Abstract: A key telephone system comprised of a key service unit connected to a plurality of local sets via four-wire conductors for providing full duplex signal communication between the key service unit and sets. Signals are carried by a first pair of each of the conductors for unidirectional transmission of signals from each set to the key service unit, and the remaining pair of conductors carries signals transmitted by the key service unit for reception by one or more of the sets. Four-to-two wire signal conversion and line impedance balancing is effected by one or more trunk circuits of the key service unit in the event one or more of the local sets are connected via the key service unit for communication between the sets and the outside telephone lines.

Abstract: A call coverage arrangement in which coverage personnel are informed of the switch-hook status of covered terminals by way of a single two-part indicator on the coverage terminal. The two-part indicator indicates switch-hook status for any one of a number of covered terminals. The first part of the indicator identifies the covered terminal and the second part defines the switch-hook status of the identified terminal. The arrangement is flexible in providing coverage for additional terminals and in providing coverage via forwarding from any termianl, since there is no need to assign and dedicate status indicators to particular terminals.

Abstract: A call processor (32) for intercepting incoming calls to a key telephone system (10) and returning a message to a calling party. A digital message storage unit (48) stores messages associating called parties with respective pseudo-telephone numbers so the calling party can input information identifying a desired called party. A CPU (50) of the call processor (32) references a look-up table (52) with hte pseudo-telephone number input by the calling party to select and transmit a message via an intercom line (36) to the key telephone system (10). The message carried by the intercom line (36) broadcasts a message relating to the identity of the called party as well as the line to utilize.

Abstract: A multiline access module for connection of a number of telephone lines to a station set. The station set is controlled by a microprocessor and communicates with the access module through a communications channel to select one telephone line for connection to the station and to read the line status, ringing, on-hook, seized, no connection, or hold, for each line; the microprocessor controlling audible and visual indicators accordingly. The access module monitors voltage levels on each line to determine the line status. Each access module includes apparatus for connection to first and second groups of telephone lines and when two modules are interconnected by an appropriately polarized cable each will activate a different connection apparatus, allowing two modules to be connected in parallel for greater line capacity.

Abstract: A key telephone system for use with at least two telephone lines that extend between a central office and two or more telephone stations. Each station is capable of responding to a manually-actuated hold select switch by establishing a hold condition on one of the lines and by connecting a line terminating impedance across the line that is to be held. Each station is further capable of monitoring the state of each line, and indicating the state of each line, without applying any indicating signals to the telephone lines. Each station furthermore determines threshold voltages for on-hook, off-hook and hold line states and determines line state by comparison of line voltage with such threshold voltages.

Abstract: Detector circuitry monitors the line voltage on a telephone line to detect an off-hook condition. In order to accomodate varying line voltages and noise conditions, the circuitry automatically selects a threshold off-hook voltage by an iterative initialization procedure which is initiated on circuit power-up. The intialization procedure repeatedly compares the threshold voltage to the actual line voltage over a period of time to eliminate false off-hook detection due to noise.

Abstract: A multiplexed data channel telephone system comprising a master station (221) and one or more remote stations (222) is disclosed. Each station (221, 222) is bridged, in a parallel electrical connection, onto a wire-pair (201) that extends from the stations to a telephone switching system. Each station (221, 222) includes a voiceband line interface (110, 310) for connecting to the wire-pair (201) at voiceband frequencies, and a radio frequency line interface (700, 800) for connecting to the wire-pair (201) at radio frequencies. Each station further includes multiplexer and demultiplexer equipment (500, 600) for frequency shifting a data channel between baseband and rf. Amplitude modulation and half-duplex transmission are used in the data channel. Telephone status and control information, including ringing and answer control, are exchanged between controllers (160, 360) via the data channel.

Abstract: A premises in which a plurality of telephone sets (10, 12) are used is provided with dedicated intercom wiring (1, 6) having its own power source. Each telephone set (10, 12) includes standard telephone circuitry (20), for communicating off premises, and also includes an intercom circuit (21). A switch (22) is provided for switching the receiver and transmitter (HS) of each set (10, 12) between off premises communications and intercom use. Each set (10, 12) includes a paging speaker (LS1) that is a part of the intercom system. To page, a button (96) is depressed at one station and the user talks into the transmitter at that station. The transmitted message is broadcasted through the speaker (LS1) at each telephone set in the system except the one that is sending the message. The intercom system control utilizes the same wire over which the audio signal is transmitted.

Abstract: A circuit for detecting a first plurality of status signals on a multiplicity of telephone lines and generating a second lesser plurality of control signals, less than the first plurality, in response thereto. Predetermined ones of the control signals are transmitted via a multiplexing circuit to a comparator circuit. A digital-to-analog converter generates analog threshold voltages for application to the comparator circuit in response to receiving command signals from a microprocessor. The comparator circuit generates a third lesser plurality of output signals, less than the second plurality, indicative of the status of a multiplicity of remote trunk circuits connected to the telephone lines. The circuit is inexpensive and occupies little circuit board area.

Abstract: The flashing light, which is used by automatic telephone call distributing equipment to indicate that incoming calls have backed up and are awaiting service, generates voltage signals the frequency of which increases with the increase in the number of calls awaiting service. The voltage signals control several relays energized one at a time and successively as the signal frequency increases, and one such relay causes the emitter-collector circuit of a transistor momentarily to conduct each time the relay is energized and deenergized, respectively. Each time the transistor conducts it energizes another relay which momentarily energizes a bell chime to produce an audible signal.

Abstract: A key telephone system comprised of a key service unit connected to a plurality of local sets via four-wire conductors for providing full duplex signal communication between the key service unit and sets. Signals are carried by a first pair of each of the conductors for unidirectional transmission of signals from each set to the key service unit, and the remaining pair of conductors carries signals transmitted by the key service unit for reception by one or more of the sets. Four-to-two wire signal conversion and line impedance balancing is effected by one or more trunk circuits of the key service unit in the event one or more of the local sets are connected via the key service unit for communication between the sets and the outside telephone lines.

Abstract: A line circuit for driving a ringer and a service indicating lamp in a telephone set, including a high frequency transformer (T.sub.2), a switching circuit (22) for intermittently disconnecting a D.C. voltage applied to the primary winding of the transformer (T.sub.2), and a control signal generating circuit (23). The control signal generating circuit generates a first control signal having high frequency and having a first duty ratio when the ringer is to be rung; and generates a second control signal having the same frequency but having a second duty ratio smaller than the first duty ratio when the service indicating lamp is to be lit. The first or the second control signal is applied to the switching circuit so that the high frequency transformer generates a ringing signal or a D.C. voltage to light the lamp. Since the high-frequency transformer is commonly used for generating the ringing signal and the D.C. voltage for the lamp, the line circuit can be made small and light.

Abstract: A telephone call routing system for routing incoming telephone calls assigns each such incoming call to a selected one or more of a plurality of agent display modules. The agent display module has a visual output indicating which of a plurality of telephone lines carries the incoming call assigned to it. Any one of a plurality of agents' telephones associated with corresponding agents' modules may be connected to the line carrying the incoming call. Each telephone has a device for generating and transmitting a coded signal along the telephone line which is answered by that particular telephone. The signal is uniquely coded to identify the agent's module which is associated with the telephone which answers the incoming call. A signal detection device detects the transmitted coded signal and decodes the signal to determine which telephone associated with an agent's module answered the incoming call.

Abstract: A telephone unit having a plurality of lines which connect to a PBX and having a microprocessor which transmits and receives data over a digital line between telephone units associated in a group such that a direct forwarding feature is controlled by the microprocessor altering the ring arrangement among the telephones in the group. The telephone unit also has a speakerphone which is controlled by the microprocessor. Each telephone unit has means for monitoring the status of the lines associated with it and providing data to the microprocessor as to line status.

Abstract: A detection circuit is provided for indicating whether a telephone line is in use or is available or is on hold. The simplified circuit can be incorporated within a telephone instrument so that no external circuitry is required.

Abstract: An extension ringing arrangement for a key telephone system wherein a plurality of key telephone sets are connected respectively through associated plurality of channel units to main equipment including a main CPU. The channel units as well as an interface unit, including a sub-CPU interconnected to the main CPU are connected in parallel to the main equipment. The interface unit is of the type used for interconnecting individual line telephone sets to the key telephone system, whereby a ringing of a selected one of the key telephone sets from a calling party is made possible, with a simple arrangement effectively utilizing existing components of the key telephone system.

Abstract: In a key telephone system, when it is impossible to set at a time the entire operation data stored in a memory device of a key station unit by using a key of a specific key telephone set among a plurality of key telephone sets connected to the key station unit, the entire data of respective operation items are divided into a plurality of data sets and then the setting of the data of respective data sets are independently set. The division of the data of respective operation items is made corresponding to the output state of a hook switch, for example.

Abstract: A solid state circuit designed to be incorporated into a telephone terminal instrument to provide a visual indication at that instrument that a telephone line to which the instrument is connected is already in use by another telephone instrument.

Abstract: A ringing signal reformatting circuit detects ringing signals having one or more ringing bursts and generates a code representing a modified distinctive ringing signal having a predetermined number of bursts and a predetermined on/off timing in response to all detected ringing signals having the same number of ringing bursts. This coded ring signal is sent to a station set and decoded thereat to generate a distinctive ring signal.

Abstract: A system is presented for accessing a plurality of central office lines, PBX, etc. by a plurality of stations and for exchanging signals between the stations. Each station is provided with a self-sufficient microprocessor which controls all the functions of the station. The microprocessors exchange control signals to indicate the status of each station and each line. A common intercom line is provided for both audio signals and control signals. Each station is assigned a unique address so that each station is able to dial up another station for intercom communication by generating the proper control signals.Each station is also provided with a switch matrix for selectively accessing any of the lines, line status indicating means, and line holding means which is automatically released when any station accesses the held line.

Abstract: A call screening system to be added onto and used with a PBX or Centrex telephone system having an attendant answering console. The call screening system enables incoming calls for various telephone extensions to be directed to another telephone extension in the system for screening such incoming calls. The call screening system includes a DTMF tone generator and a screening system. The DTMF tone generator is coupled to the attendant answering console for generating a first DTMF coded signal for enabling the attendant answering console to call a screening telephone extension within the telephone system and generating a second DTMF coded signal that provides an indication as to the particular telephone extension within the telephone system for the person that the incoming caller is calling. The screening system is coupled between a single tip/ring line from the PBX or Centrex and a tip/ring line to a screening telephone extension of a user screening incoming calls for other telephone extensions.

Abstract: Apparatus disposed at location of a key telephone system and associated with the system to produce a substitute signal and a substitute alarm in the presence of a ringing voltage when the system is deactuated. The apparatus comprises: an electrically powered lamp for displaying the substitute signal when a first voltage is applied thereto; an electrically powered device for sounding the substitute alarm when a second voltage is supplied thereto; a second source; and a circuit arrangement coupled to the first and second sources, the line, the lamp and the device. The arrangement, when the system is deactuated in the presence of the ringing voltage, produces the first and second voltages and applies same to the lamp and device respectively to cause the substitute signal to be displayed and the substitute alarm to be sounded.

Abstract: There is disclosed a communication system and operating method wherein the manner in which all telephone calls are displayed at a station set allows uniform user operations to originate and terminate those calls. This is accomplished by having all calls dynamically assigned to the same set of general call appearances (buttons on a multibutton station set). There are no call appearances that are dedicated to specific call types. This allows the station set user to perform the same set of operations on all calls by using the same sequence of physical operations independent of the type of call. Additionally, the system may reserve one call appearance button at a station set for special use.

Abstract: A multi-line, multi-instrument telephone system having no key service unit and wherein decentralized or local indicator lamp and paging circuit management functions are provided which are operative independently in each station set to operate and control the indicator lamps and paging circuits through selective local generation and alteration of control signals and comparison of the control signals with locally generated reference voltage signals to provide basis for decisions on required visual and audible indicator status. The system is connected in loop fashion with each instrument being connected across a common, multiconductor buss wherein a single conductor supports lamp supervision signaling for the multiple lines and another single conductor supports intercom status signaling, intercom audio, paging audio, and the ring signal.

Abstract: A stand-alone keyphone system that is designed to be installed at any location where it is desired that a plurality of telephone lines be available to each of many user points. The system operates independently of all other systems and without the need for a KSU or a central control unit. Each system allows a plurality of telephone lines to be connected and operated simultaneously and a plurality of systems may be connected within each installation with minimal loading of telephone lines. The system comprises, within a single housing, a DTMF telephone set and a key adapter set that further comprises all the mechanical and electronic circuits to operate the system including a switching subsystem and hold circuit subsystem. The system incorporates a hold pushbutton for placing any of the telephone lines on hold, a set of four telephone line accessing pushbuttons; and a set of line status LED's that indicate if the corresponding line is idle, ringing, busy or holding.