Abstract: A line circuit for a key telephone system using as the main operative components, two relays i.e. a ring relay and a combined off-hook and hold relay and an optical coupler and rectifier bridge combination. On a ring signal from the exchange, the optical coupler is activated to cause the energization of the ring relay. On a station of the line going off-hook, the conventional A lead ground operates the off-hook relay and causes de-energization of the ring relay. When a station of the line goes into hold, the circuit must differentiate this condition from a hang-up condition. This differentiation is performed by the coupler sensing the line voltage as low or high. The line voltage is high if the line loop is open indicating a hang-up condition. The line voltage is low if the line loop is still closed during the sensing period as a preliminary to the hold condition. The off-hook relay is held during this sensing operation so that the circuit may enter the hold condition when indicated.

Abstract: A line circuit for a key telephone system using two relays, a ring delay (B) and a combined off-hook and hold relay (C), and solid state devices including a first and a second optical coupler. On a ring signal from the exchange, the first optical coupler is activated to cause the energization of the ring relay. On a station of the line going off-hook (busy), the conventional A lead ground operates the C relay and causes de-energization of the B relay. When a station of the line goes into hold, the circuit must differentiate this condition from a hang-up condition. This differentiation is performed by sensing the line voltage as low (continued loop closure at the start of hold) or high (open loop at the stations of the line). The C relay is held during this determination so that the circuit may enter the hold condition when indicated.

Abstract: This system employs the standard single line tone dialing telephone instrument, connected via (typically) existing 4 conductor 22 gauge wire. A telephone hookswitch sensing circuit provides a trigger to connect a tone decoder across the talk path for a period of time established by a time delay circuit. When the instrument is tone dialed, the output of the tone decoder is fed respectively to: a gate circuit which switches the telephone instrument from the local intercom battery to an outside telephone line; a HOLD feature circuit which places the outside call on HOLD; a remote control circuit which turns on and off devices remote from this system; or to individual bells of other instruments within the system.

Abstract: The invention is concerned with the interconnection of communications units such as telephones, microphones and loudspeakers. According to the invention a connecting plate extends between the undersurfaces of adjacent units and locates the units in the desired spatial relationship. Jointing means then detachably connect the unit to the plate.

Abstract: After description of a number of prior art automatic telephone number identification systems and certain problems associated therewith, a new method and apparatus for use in such systems which overcomes the problems of the prior art is described. In its preferred form, the method includes the steps of applying to the telephone line at a central office a voltage which has a magnitude sufficient to produce a first predetermined value of loop current in the telephone line. At each party station, the loop current is caused to change between the first predetermined value and a second predetermined value in a manner unique to that party station, with the second predetermined value being smaller than the first predetermined value but greater than a value of loop current that would signify to the central office that an on-hook condition exists on the telephone line.

Abstract: The invention relates to a fastening arrangement in a telephone instrument of the one-piece type for both the earphone capsule and the cap which cap should be fastened to the casing in order to cover the opening of the head part. The arrangement has two elements. The first element is a body which is secured to the inside of the casing in the top of the head part, and two oppositely directed tongue-formed parts. The first part, directed upwards, engages an upper collar-formed socket on the inside of the instrument cap and the second tongue-formed part contacts the upper front surface of the earphone capsule. The second element is a body with a rear projection engaging an aperture of a printed circuit card mounted inside the throat of the casing and two oppositely directed tongue-formed parts. The first of these parts contacts the lower front surface of the earphone capsule and the second engages a lower collar-formed socket on the inside of the instrument cap.

Abstract: A centrally located polling system uses conventional telephone dial networks and a means for digital telecommunication to periodically interrogate remote site alarm installations for security related information. Apparatus at the central location retrieves remote site telephone numbers from memory and controls dialing sequences to establish communication exchange between the central and remote sites. Circuit means are provided to validate the communication link, or alternatively, retry the dialing sequence. Apparatus at the remote site continuously monitors the status of a plurality of alarms and is responsive to requests from the central location by means of the telephone dial network. The remote site security status thus transmitted is received and digitally displayed in coded form at the central location.

Abstract: A PBX call restriction arrangement is disclosed in which a plurality of call rerouting schemes are concurrently provided. The class of service assigned each station is used to define both the types of calls prohibited to the station and the rerouting treatment to be given an attempt by a subscriber at this station to make this prohibited type of call.

Abstract: Apparatus for enabling a user to selectively defeat the toll-call restriction system. The apparatus is comprised of means for applying a tone to the telephone lines through the calling telephone mouthpiece. Detection means responsive to the tone sets a flip flop which functions to inhibit the activation of a relay normally used to disrupt the connection between the calling phone and telephone lines when an unpermitted telephone number is dialed.

Abstract: A key telephone system signal priority arrangement is disclosed wherein each type of call in a key telephone system is assigned a distinctive priority. When a call is directed to a station engaged in an existing lower priority call, a warning tone is given to both parties engaged in this existing call. The existing call is then automatically placed on hold while the preempting call is completed to the called station such that the called station can answer the preempting call "hands-free".

Abstract: Magnetic flux generated in a core of a transformer employed in a transmission network by subscriber loop direct current is compensated by controllably generating a current to induce a magnetic flux equal and oppositely phased to that induced by the loop current. This is achieved without need for an additional transformer winding other than the normal coupling windings by employing a current sensing element in circuit with the normal primary transformer winding which is effectively electrically isolated from a controllable current source connected in circuit with the normal secondary winding. The magnitude of the compensation current supplied to the secondary winding is controlled via the primary current sensing element. Negative feedback enhances the stability and linearity over a desired current range. Isolation between the primary and secondary circuits is realized by employing optical isolators, each including a light emitting diode and associated phototransistor.

Abstract: A device for monitoring and controlling equipment, such as an agricultural irrigation system. The device can be called by an ordinary telephone from anywhere in the world and after answering the telephone the device will monitor and indicate to the caller the system status, that is, whether the system and certain system parameters are operating. If the caller is calling on a conventional Touch-Tone* telephone the caller can then access the system with a confidential three digit access code. (*Touch-Tone is a registered Trademark of the American Telephone and Telegraph Company.) If the system recognizes and verifies the access code the calling operator, with the use of two digit commands, can start and stop system components as well as monitor those and other components to assure that the controlled system is operating properly.

Abstract: In a digital communication system, synchronization of a plurality of asynchronous digital signals is usually achieved by stuffing one or more pulses in a pulse stream. Thereby, stuffing equalizes the input signal bit rate with the usually fixed bit rate of a signal on a transmission link. For example, in pulse stuffing, single pulses are added at certain allowed times to equalize the input bit rate with the transmission link bit rate. On the other hand, in block stuffing, a block of pulses is added. However, conventional block stuffing usually requires a narrowband phase-locked loop for removing jitter in the received signal. As a result, slower acquisition of synchronization occurs.

Abstract: A toll restrictor access circuit for use with a plurality of toll restrictors shared by a group of telephone lines is disclosed. The access circuit connects a toll restrictor to a telephone line when a call is initiated so that the number dialed by the caller can be monitored to determine whether the number being dialed is one that is authorized. The toll restrictor controls a polarity reversal relay in the access circuit to disable the telephone dial until a dial tone is detected. If the caller dials a valid number, the toll restrictor energizes a permit relay in the access circuit which allows the call to be completed in the normal manner. The permit relay also de-energizes the polarity reversal relay thereby disabling the telephone dial and releases the toll restrictor so that it may be used by another telephone line. If on the other hand the caller dials a prohibited number, the toll restrictor energizes a restrict relay which disconnects the telephone instrument from the telephone line.

Abstract: An adaptor to be used with a standard telephone to enable a plug-in headset to be used therewith without interfering with normal usage of the telephone and to allow usage without the necessity of employing the normal telephone handset, enabling free use of the user's hands. The attachment includes a latching push-button which operates a switch assembly which duplicates the function of the telephone hook switch assembly. The attachment is mounted on a bracket which is clampingly engageable with the telephone and which carries the jacks for the plug-in headset and the latching push button and substitution switch assembly. The attachment allows simultaneous use of the plug-in headset and the normal telephone handset by two persons for a conference call.

Abstract: A multiple contact switch has a plurality of contact areas spaced across a base member, a plurality of cantilevered spring contact members mounted side-by-side on the base member with contact portions overlying the contact areas, and a rotary cam member extending over the spring contact members to push the contact members down to make contact. A cam surface is provided for each contact member. The cam member is actuated by a remove actuating member and in a line switch for a telephone set, the switch can be mounted on the base of the telephone set with the cam actuated by a flexible cable which in turn is actuated by means depressed when a hand set is replaced.

Abstract: The detachable communications headset described herein is all acoustic, comprising support means for a transmitter tube and a receiver tube and for supporting the headset on the user's head. The transmitter and receiver tubes are detachably coupled to communications equipment remote from the headset. All electronic components necessary for radio and telephone communications are remote from the user's head.

Abstract: Subscriber stations in a telecommunication system are selectively connected and controlled by an exchange having a central control. The subscriber stations have operating conditions varying from an idle to a start condition and from a captive to the idle condition. Line connection circuits of the subscriber stations issue a signal indicative of a transfer of any subscriber station from the captive to the idle condition. Circuits common to the subscriber stations but separate from the central control monitor the subscriber stations as to the issuance of a signal indicative of a transfer of a subscriber station from the captive to the idle condition. Circuit components common to the subscriber stations and connected to the monitor circuits ascertain the particular subscriber station for which an indicative signal has been issued and carry out a release of the particular captive condition.

Abstract: A holder for microphones and the like, attachable to a vertical wall and having a ledge member whereon the usual mounting button of a microphone is caused to rest by the force of gravity and a spring member fixed relative to said ledge member. Said spring member is formed with a slot, and the resiliency of said spring member urges said button to a position on said ledge member. Such resiliency can be overcome to enable said button to pass clear of the ledge member when desired for removal of the microphone.

Abstract: An intercom system for single-line customers is disclosed which utilizes the existing nonkey telephone sets and four-conductor wiring plan together with an additional adjunct per telephone and a common control unit. Hold, broadcast intercom, and their associated visual signals are controlled by each adjunct unit which is interposed between the associated telephone set and the existing four-conductor telephone cable. Normal voice signals and supervision are transmitted using one pair of the four-conductor cable. The second pair of the cable is used for signaling between the common control unit and the adjuncts as well as for supplying power to the adjuncts. The operation of a single nonlocking key at any adjunct places the system in the intercom mode and concurrently places an active central office line on hold. Conclusion of an intercom conversation is accomplished when all telephone sets go on-hook. A held central office line is then connected to the next party to go off-hook.