Abstract: A system and method are disclosed for automatically disabling call communications through a switching system until answer supervision is received for the call. A four-wire switching system includes a fraud control unit which disables communications over the established transmit portion of a four-wire call connection through the switching system and prevents normal communications from a calling to a called line. However, normal call progress signals are allowed to pass on the established receive portion of the call connection from the called to the calling line. The fraud control unit includes a generator for generating idle code and a selector for inserting either the idle code from the generator or caller communications on the transmit portion of the call connection from the calling to the called line. The selector is controlled by a selector control unit under the control of the central processor of the switching system.

Abstract: A detector circuit detects one of two impedances presented by a communication line for each one of a plurality of operative modes. The circuit comprises a network having three parallel branches. The first includes two serially connected resistors which develop a reference potential in response to current flowing in the line. The second branch includes two oppositely poled light-emitting diodes (LEDs) which form a sensor to detect current flow in the line in either direction. The third branch includes a varistor to limit the magnitude of unexpected potentials applied to the sensor. When the magnitude of the reference potential is sufficient to forward bias either LED and the magnitude of the current is greater than a predetermined level, one of the LEDs will generate an output signal representative of one impedance of the line. Otherwise, the LEDs generate a second output representative of the other impedance of the line in a particular operative mode.

Abstract: For use in a multichannel time division multiplexed conference arrangement where the samples in one time frame of simultaneous speakers are summed for distribution to each of the conferees, the disclosed arrangement reduces the amount of speech that is often not heard (clipped) when a conferee first begins to speak. The arrangement features a delay unit which stores all the speech samples from one time frame for a period of time greater than the processing time required to detect and determine whether to include speech samples from a new speaker in the distributed sample. By first storing the samples from one time frame and then summing the stored samples, any samples from a new speaker may be included in the resulting output sample to reduce speech clipping.

Abstract: For use in multiport digital conference arrangements adapted to sum speech samples of selected speakers, the disclosed method and apparatus improves the quality of communication by holding over selected ports for varying time intervals depending on the interval of speech above a threshold. Furthermore, a minimum number of ports is always enabled to provide background noise when all the conferees are silent.

Abstract: For use in multiport digital conference arrangements wherein the speech samples of selected speakers are summed for distribution to the conferees, the disclosed arrangement features processor-controlled switching hardware responsive to a control signal from a conference control processor. Generated in response to a request from a port for priority treatment, this control signal designates particular conferees as having assigned priority treatment such as attendant and broadcast priority in the speaker selection process. In addition, the arrangement also includes a speech detector for each port. By evaluating the conferee's assigned priority treatment, the conferee's speech level, and other factors, each conferee is dynamically assigned an adjusted priority level by a conference processing program. The speech samples of only the highest priority level conferees are summed to control various types of distortion and to permit designated conferees to be always heard by the other conferees.

Abstract: For use in multiport digital conference arrangements wherein the speech samples of selected speakers are included in an output sample for distribution to the conferees, the disclosed arrangement features a speech detector for each port and processor-controlled switching hardware. By evaluating the conferee's speech level, the current state of the port, and other factors, each conferee is dynamically assigned an adjusted priority by a conference processing program. The speech samples of only the highest priority conferees are summed to control noise level, singing caused by echo, and other types of distortion.

Abstract: An arrangement for indicating when different types of electrical components, such as circuit boards and the like, are concurrently joined with connector assemblies. Common to the connector assemblies is a plurality of output conductors which is connected to corresponding plurality of output terminals positioned on each of the connector assemblies, respectively. On each component is a plurality of identification conductors arranged to identify the component through the application of a distinct pattern of potentials on the output conductors when one of the components is joined with one of the connector assemblies. When different types of components are concurrently joined with associated connectors, the identification conductors interconnect all the output conductors, such that only a predetermined pattern of potentials other than the distinct patterns may be applied to the output conductors.

Abstract: A detector circuit for detecting the on-hook and off-hook states of a communication line includes current and voltage sensors for generating two reference signals. One signal represents the current flowing in the line; the other represents the voltage on the line. A comparator circuit compares these two references to generate an output signal representative of the on-hook state when the magnitude of one of the references is greater than the other. When the magnitude of the one reference signal is less than the other, the comparator circuit generates another output signal representative of the off-hook state of the line. In addition, when the line is electrically isolated from ground, the two comparator output signals may drive an opto-isolator to generate two corresponding output signals electrically isolated from the comparator output signals.

Abstract: An electrical keying arrangement ensures that correctly associated electrical components, such as a circuit board and connector, are interconnected by completing a conducting path which includes two pairs of keying terminals positioned on the components. One pair of uniquely spaced and positioned keying terminals on the edge of the circuit board are strapped together to complete the conducting path through the other pair of keying terminals when the board is inserted in the connector. The path is completed only when the connector keying terminals are similarly, uniquely spaced and positioned. When completed, the path may be utilized to energize a relay which controls the application of power to the circuit board.

Abstract: In a telecommunications switching system having a central processor for generating control signals, peripheral units, and a power source terminal, a power control arrangement includes a plurality of power switches for selectively connecting and disconnecting the peripheral units and the power source terminal in order to minimize power consumption. Responsive to peripheral unit control signals, a power control unit, which is included in the arrangement, controls the operation of the power switches so that only those peripheral units designated by a control signal are connected to the power source terminal. After the peripheral units have been operated, the power control arrangement disconnects the operated peripheral units from the power source terminal.