Abstract: A lines status sensor provides for monitoring of the operating status of one or more telephone lines at an associated telephone station apparatus. The lines status sensor includes a translation circuit being responsive to potential differences appearing across the telephone line, for generating a voltage signal of corresponding polarity in relation to a reference voltage. A voltage divider circuit provides the reference voltage in addition to a first limit voltage being of a more negative potential than the reference voltage, and a second limit voltage being more positive than the reference voltage.

Abstract: An area voice paging feature is provided in a key telephone system wherein key telephone station sets each have a loudspeaker circuit responsive to a d.c. control signal, on an associated signalling path, to audibly reproduce voice band signals superimposed on the d.c. control signal. A page control interface circuit generates a page control signal in response to receiving the d.c. control signal, when the d.c. control signal is directed to the interface circuit on one of the signalling paths, and generates a d.c. biased voltage signal having an a.c. component corresponding to the voice band signals. Page switches each have an output connected in common with a predetermined respective one of the signalling paths and are each responsive to the page control signal to couple the d.c. biased voltage signal to the respective signalling path. Each loudspeaker circuit, in a group as selected by the page switches, receives the d.c. biased voltage signal and produces and audible signal corresponding to the a.c.

Abstract: A line circuit includes a fixed resistance feed consisting of a pair of resistors connected in series with a d.c. power source and tip and ring leads of a communication line. A variable current feed includes a current sink and a current source also connected in series with the d.c. power source and the TIP and RING leads. Energizing current flow in the communication line results as the combination of currents passed by the two feeds. A control circuit determines the currents conducted by the current source and current sink and introduces variations in these currents in accordance with signals for transmission along the communication line. Differences between current flows in the variable current feed and current imbalance conditions on the communication line are accommodated by the fixed resistance feed which also determines the terminating impedance for the communication line.

Abstract: First syllable clipping typically associated with simple control circuits in hands free telephony, is substantially reduced by using a voice switch with non-linear response characteristics. The voice switch includes field effect devices in transmit and receive variolossers for providing hands free operation in communication apparatus. The field effect devices are non-linear in their response to a control voltage, and are thus controllable to provide rapid switching from an idle mode of operation, to an opposite mode of operation. The control circuit generates a control signal for operating the voice switch in response to a.c. signals in a microphone circuit connected with a transmit path and in response to a.c. signals in a loudspeaker circuit connected with a receive path.

Abstract: A hands free answer feature is provided in a key telephone system which includes an intercom lead pair for providing intercommunication between key telephone station sets and a signalling path for providing audible signals via a loudspeaker circuit in the key telephone station sets. The hands free intercom feature is provided by the addition of a hybrid circuit including first and second unidirectional signal paths for coupling a.c. signals between the intercom lead pair and the signalling lead. A d.c. control signal having first and second d.c. signal states is generated on the signalling lead in response to a ratio of amplitudes of signals in the first and second signal paths being greater or lesser than a predetermined ratio. The loudspeaker circuits each include a receive signal path connected to a loudspeaker. A transmit path and path switching circuitry are added to the loudspeaker circuit. The path switching circuitry is responsive to the first and second states of the d.c.

Abstract: A manual cutover apparatus activates a plurality of circuit boards in an equipment frame in a telephone switching facility. Each circuit board is provided with a manually operable switch for inhibiting the function of the circuit or disabling a line termination at the circuit board, while the switch is in contact with an elongated control member. The control member spans the board locations in the frame and is held in place by slots in a connector shroud at each board position. When the frame is empty of circuit boards, the control member is inserted into slots in the equipment frame. After the required circuit boards are placed in the frame, these boards are activated by the withdrawal of the control member through a hole in a frame member at one end of the frame. The switch includes a base with a pair of terminals and a cantilever spring switch member extending over a groove in the base.

Abstract: In a telephone switching facility, line circuits are arranged in groups, each including a local ringing battery bus, and a universal high level signal generator (UHLSG) for providing ringing and other high level signals to the line circuits via the local ringing bus. Each generator is responsive to address signals from a controller in the switching facility to generate selected high level signals. The UHLSG includes a switching bridge driven by a width modulated signal stream of periodically occurring pulses having assertion times suitable for developing a high level signal across a network at the output of the switching bridge. The width modulated pulses are generated from period and time signals. The period signal occurs once with each sequence in repetitively generated data byte sequences. The time signal occurs with correspondence between a selected stored data byte and an instant one of the data bytes of the sequence. A plurality of the stored data bytes are arranged in ranges in a storage circuit.

Abstract: A subscriber loop test device is connected across a subscriber loop adjacent a subscriber equipment and remote an associated switching office. The subscriber loop test device includes a relaxation oscillator and a connection circuit responsive to a predetermined high voltage applied at the switching office for connecting the relaxation oscillator to the subscriber loop. The relaxation oscillator responds by drawing an energizing current which it modulates at the operating frequency of the oscillator. Detection of this frequency in the switching office verifies the DC and the AC continuity of the subscriber loop. Additional contacts in the connection circuit are used to disconnect the subscriber apparatus for the duration of the operation of the test device so that faulty subscriber apparatus will not interfere with verification of subscriber loop serviceability.