Abstract: A protective circuit for use in a subscriber's telephone circuit that includes a repertory memory and includes a battery which provides memory retention current. Circuitry permits the battery to be protected by a series current limiting resistor while maintaining sufficient voltage so that the memory maintains its integrity.

Abstract: A series regulator responds to an input voltage to produce a constant direct voltage. A resistor is connected at one end to the output of the regulator. A current carrying bus is connected between the other end of the resistor and the input of the inverter whereby current flows through the resistor producing a voltage drop thereacross and thereafter flows into the inverter to supply power thereto. An electronic switch has a closed position at which current on the bus supplied via the resistor is augmented by the current on the bus supplied via the switch. The switch has an open position at which the augmented current is not present on the bus, the switch being placed in the open position whenever a pulse appears in the control voltage and thereafter is placed in the closed position when the pulse disappears and said voltage drop is at least equal to a preselected value.

Abstract: A secretarial answering system for use with a switching system which includes a plurality of subscriber telephone stations each equipped with a buzzer, and a secretarial telephone station equipped with an audible signalling circuit and a plurality of lamp and switch pairs. A line circuit is connected to each subscriber station and monitors its busy, idle and ringing status. A processing unit periodically scans the line circuits to determine changes in the status of the subscriber stations. This processing unit then transmits subscriber station status and identification information to the secretarial telephone station. The secretarial station uses this information to provide visual and audible indications of subscriber station status. In response to operation of the switch associated with a called subscriber station, a directed call pick up or a call transfer message is transmitted by the secretarial station to the switching system.

Abstract: A secretarial telephone station for use with a secretarial answering system and a switching system which includes a plurality of subscriber telephone stations each equipped with a buzzer. The secretarial answering system is connected to the subscriber stations and transmits subscriber station busy, idle and ringing status and line identification information to the secretarial station. The secretarial station includes a lamp and switch pair for each subscriber station, a processing unit and an audible signalling circuit. The processing unit receives this information and causes the lamp associated with each of the subscriber stations to display dark, lit or flashing signals corresponding to the idle, busy and ringing status. The processing unit also causes the audible signalling circuit to provide a ringing tone wherever a lamp is flashed.

Abstract: A protective circuit consisting of two diodes which functions along with other external circuit elements to provide protection against transients for an integrated circuit utilized to generate dial pulses in an electronic telephone circuit. By means of included diodes, excessive transients are prevented from entering the integrated circuit internal circuitry and disturbing the memory included therein or other operational characteristics.

Abstract: A circuit which unlocks the signaling circuit of a feature telephone station after it has been locked. A microprocessor disconnects a tone generator from an associated keypad upon detection of operation of a lock button. The microprocessor subsequently connects the tone generator to the keypad upon detection of operation of the lock button and a predetermined master unlock code provided via the keypad. The microprocessor also connects the tone generator to the keypad upon detection of operation of the lock button followed by simultaneous operation of a predetermined plurality of telephone feature buttons.

Abstract: A hold circuit for use with a single line telephone which may or may not be equipped with extension instruments. The circuitry in response to the momentary operation of a manual switch actuates a siliconcontrolled rectifier to place a resistive load across the telephone line thus allowing the subscriber at the basic telephone instrument to go "on hook". Subsequent removal of the basic instrument handset from the hookswitch or an extension phone going "OFF HOOK" will cause the resistive load to be removed. Also included is a hold release circuit which automatically disconnects the hold circuit after a predetermined period of time.

Abstract: A current regulated pulse dialer circuit including a memory for storing predetermined sequences of telephone numbers, for use in a loop powered pulse dialing telephone. A first current source is connected to an electronic pulse dialer to provide a high impedance across the telephone line during transmission and interpulse pause conditions and a second current source is connected to an electronic pulse dialer to maintain the integrity of information stored in the memory portion of the dialer circuitry.

Abstract: A telecommunication network has a plurality of tandem node switches interconnected by trunks. Each switch generates message detail records (MDR) which are transmitted by data links to a network control center. In response to complaints, an NCC operator can start a mechanized search of MDR to retrace the path a call had earlier taken. The retraced path may be graphically illustrated on a display network map. Data from each call trace may be stored in a call trace log for subsequent retrieval.

Abstract: A telecommunication network includes a number of switches interconnected by groups of trunk circuits. Trunk traffic data is generated by the switches and transmitted to a network control center where it is stored in a traffic database. The network control center includes a system for mechanically generating periodic traffic reports and performing calculations leading to recommendations pertaining to additions or deletions of the number of trunks in a group necessary to maintain an optimum size network.

Abstract: A telecommunication network has a plurality of tandem node switches interconnected by trunk circuits. A network control center controller mechanically administers internodal conference calls by storing data pertaining to a scheduled conference call. Prior to the scheduled time, the data is downloaded to the tandem node switches which set an internodal conference bridge. Participants in a conference call first dial a bridge access number and then a password which assures security.

Abstract: Apparatus is adapted for connection to an alternating current source and a direct current power supply powered by the source. The supply is enabled when the source is operative and disabled when the source is inoperative. The apparatus utilizes first, second and third terminals. A power line monitor is connected at its input to said source and at its output to said first terminal. The monitor maintains the first terminal at a selected potential when the source is enabled, and is unable to maintain the first terminal at any potential when the source is disabled. A first circuit connected to the supply, a battery and the second terminal to charge said battery and to maintain the second terminal at a selected potential when the supply is enabled. The battery maintains the second terminal at the selected potential when the supply is disabled. The first circuit is connected via a resistor to the first terminal to maintain the first terminal at a different potential when the monitor is inoperative.