Abstract: A house intercom security system includes a main unit connected between the exchange line of a telecommunication office and a telephone set, an indoor intercom and an outdoor intercom respectively connected to the main unit, and an alarm connected to the main unit. The main unit is driven to dial a pre-set telephone number when a visitor presses on the outdoor intercom, as the host of the house in which the house intercom security system is installed is absent. The indoor intercom is driven to trigger the alarm and to dial a pre-set telephone number for help when the user presses on an alarm button of the indoor intercom.

Abstract: A system and method provide the capability for a visitor to a home or business to leave an audio message for the occupants if they are not present. Outside the home or building, an interface may be provided which is proximate to a doorbell which a visitor may employ when notification by the doorbell has proved unsuccessful. Actuation of a switch on the interface may activate a messaging system which will retrieve a stored phone number and establish a telephonic connection over a telephone network. The telephonic connection may be with a voice messaging system which, in turn, will broadcast via a speaker incorporated into the user interface, a greeting recorded by the occupant. At the end of the greeting, a visitor may then speak into a microphone incorporated into the user interface, and record an audio message. The controller may further be programmed to establish a telephonic connection remotely located between the visitor interface and a telephone.

Abstract: A non-KSU message delivery system enables any station within the non-KSU system to automatically answer incoming calls and prevents more than one station from automatically answering the incoming calls. The non-KSU system allows for distributed recording of voice messages and allows transferred calls to be answered by a specific station's voice mail. The non-KSU system also stores an incoming caller's calling party identification information at a station if the incoming call is either manually or automatically answered by the particular station.

Abstract: A network-based intercom system and method comprises software and the necessary portions of a computer network on which it is implemented. The software includes a dispatcher module to be installed on any of the computers of the network, and an intercom module to be installed on each of the participating computers in the system. The system has the advantage that it can be installed on non-dedicated computers, thus avoiding costly and inconvenient wiring and hardware installation. The system provides automatic message receipt without unnecessarily interrupting a recipient. This is achieved by signaling that a message has been sent by an assigned audible tone that is unique to the addressee. Thus, the recipient becomes aware that he or she has automatically received a message. The message is displayed in a banner on the addressee's computer monitor for selective viewing based on an order of priority. A recipient can respond directly to a message by interfacing with a visual display associated with the message.

Abstract: A method and system for communicating without use of manual contact with a communications unit. The user approaches a communications system and can activate a communications unit by a proximity/motion detector and/or a voice activation device. The person can generate audio signals, such as by voice command, to activate the unit and establish contact. Body movements can also be used to connect to a specific location and/or control the communications mode, such as private, semi-private or conference call mode.

Abstract: The invention makes it possible to call a resident of collective housing even when a room number of the resident is unknown. A collective housing entrance substation is connected to residential master stations through a controller thereof, and a name retrieval module is connected to the controller, the name retrieval module having a memory in which a name and/or room number of a resident is registered in advance, a button operated to display the name and/or room number of the resident registered in advance, a name indicator for displaying the name and/or room number of the resident registered in advance, and a call button that is operated with the name and/or room number of the resident registered in advance displayed to call the residential master station of the resident.

Abstract: A method and system for providing a paging feature to a particular group of telephones in a multiline telephone system are described. In one embodiment, a method is presented for providing an one-way communication among a selected group of telephones in a KUS-less telephone system having a plurality of telephones. A group number is assigned to each of the plurality of telephones in the system. A group number is selected at a paging telephone selected from the plurality of telephones. A one-way voice communication is set up automatically through a voice channel of the telephone system to a group of telephones having the selected group number.

Abstract: A network-based intercom system and method comprises software and the necessary portions of a computer network on which it is implemented. The software includes a dispatcher portion to be installed on any of the computers of the network, and an intercom module portion to be installed on each of the participating computers in the system. The system has the advantage that it can be installed on non-dedicated computers, thus avoiding costly and inconvenient wiring and hardware installation. The system provides automatic message receipt without unnecessarily interrupting a recipient. This is achieved by signaling that a message has been sent by an assigned audible tone that is unique to the addressee. Thus, the recipient becomes aware that he or she has automatically received a message. The message is displayed in a banner on the addressee's computer monitor for selective viewing based on an order of priority.

Abstract: A method of establishing a private audio communication channel on an intercom system (100) having a plurality of intercom units (101-1 to 101-n), is diclosed. The intercom system 100 is activated by spoken request data input via at least one of the intercom units (101-1 to 101-n). Audio data is transmitted to substantially each of the plurality of intercom units (101-1 to 101-n) in response to the spoken request data. A private audio communication channel is established between at least two of the plurality of intercom units (101-1 to 101-n) in response to spoken reply data input via any one of the plurality of intercom units (101-1 to 101-n).

Abstract: A wall-hung or shelf situated free-standing voice memorandum system allows an individual to record a message for another member of the household. the system can be used in connection with a household doorbell system so that at the user's choice, the system either operates simply as a doorbell or when the door button is pressed plays at the door a greeting that the user has recorded, invites the visitor to leave voice messages for the household-and-records any messages given.

Abstract: A personal communications system has a plurality of personal communications units defining a network. The personal communications units are configured to send and receive digital communications among one another via the network. A wireless interface adaptor further defines the network and is configured to function as a repeater. The personal communications units are configured to cooperate with the wireless interface adaptor when the wireless interface adaptor is available. The wireless interface adaptor coordinates access of each personal communications unit to at least one other personal communications unit. The personal communications units are further configured to cooperate with one another to effect communications therebetween when no wireless interface adaptor is available.

Abstract: An automatic door answering system comprises a door intercom system, a recording machine, a telecommunication system, first, second and third interfaces, and a microprocessor-based switching device. The switching device is coupled to the door intercom system, the recording machine, and the telecommunication system by way of the first, second, and third interfaces, respectively. The switching device switches back and forth between coupling the door intercom system to a telecommunication system, coupling the door intercom system to a recording machine, and coupling the telecommunication system to the recording machine. If the recipient of a visitor is not available, the automatic door answering system establishes a communication link between the visitor and the recipient using the door intercom system and the telecommunication system. If the recipient of the visitor is not available, the automatic door answering system allows the visitor to record a message for the recipient.

Abstract: A pager system connectable to the existing telephone wiring for activation through the normal residential DTMF telephone instruments, the system including a plurality of pager devices, each connected to the phone line between the tip and ring wires, and each pager including an identification circuit to allow it be individually addressed by a person using the phone, whether or not connection has been made through the central office. For use of the system, the keypad of the telephone instrument is used to enter a sequence of characters (e.g., symbols as well as numbers), which comprise an activation sequence. The DTMF activation sequence includes three parts: a header, a pager address (pager identification PID) and a signal identification (SID). The header portion is a sequence which is not used by the central office as part of its available services. The header portion is a system enabling signal that distinguishes the pager system from central office sequences.

Abstract: In the microprocessor assembly of the base station (51) and of the mobile station of a wireless telephony device, a reduced-intercom mode is implanted intended for sound monitoring, which mode, once it is started from the base station (52), brings about the succession of the following events (53):reception in the mobile station by radio channel of the instruction to install in the reduced-intercom mode consisting of the inhibition of the ringing, the switching on of its microphone, the switching off of its loudspeaker and the automatic calling of the base station to cause the latter to switch on the loudspeaker and switch off the microphone, so as to establish an automatic calling of the mobile station from the base station (54).

Abstract: A method for automatically providing voice paging information of a caller in a switching system having an automatic attendant function. The method includes the steps of controlling an automatic answering machine equipped in the switching system upon receiving an incoming call, thereby outputting an announcement message containing a voice paging announcement message, and waiting for input data from the caller. When voice paging request data is received during the waiting for the input data, the automatic answering machine is controlled to output a voice paging announcement message, thereby establishing a voice paging channel. The switching system also broadcasts a voice paging signal received from the caller, waits for a response of an extension subscriber, and establishes a channel for the incoming call when the extension subscriber responds, thereby executing a call service associated with the incoming call.

Abstract: A method for embodying an automatic call during an idle state. The method for embodying the automatic call in a keyphone system, where an extension number of counterpart's keyphone for automatic call is registered in correspondence with a keyphone system capable of embodying the automatic call, thereby connecting the automatic call upon the two keyphones under the idle state.

Abstract: A method for making an automatic call for a designated pair of key telephone sets attendant on a key telephone exchange system. The method includes the steps of designating a specified pair of key telephone sets to be served the automatic call therebetween in an idle state of the pair of the key telephone sets, and storing information of the designated key telephone sets into the key telephone exchange system; and causing either one of the pair of the designated key telephone sets to be connected on the automatic call with the other one of the pair of the designated key telephone sets, responsive to a request for the automatic call by either one of the key telephone sets designated, the key telephone sets being in an idle state.

Abstract: A distributed processing telephone system for providing "plug-and-play" capability. In particular, a key telephone system comprises a plurality of telephone sets. Each telephone set is coupled to a least one common communications channel, or telephone line, and includes at least one tunable RF modem. There is no key service unit (KSU). That is, the system is KSU-less. Resources of the telephone system are allocated using a peer-to-peer protocol. For example, as each telephone set is newly added to the system, the new telephone set adaptively determines its own allocation of resources, e.g., intercom numbers, etc. During operation, each telephone set requests the appropriate resources from its peers.

Abstract: A distributed processing telephone system for providing "plug-and-play" capability. In particular, a key telephone system comprises a plurality of telephone sets. Each telephone set is coupled to at least one common communications channel, or telephone line, and includes at least one tunable RF modem. There is no key service unit (KSU). That is, the system is KSU-less. Resources of the telephone system are allocated using a peer-to-peer protocol. For example, as each telephone set is newly added to the system, the new telephone set adaptively determines its own allocation of resources, e.g., intercom numbers, etc. During operation, each telephone set requests the appropriate resources from its peers.

Abstract: A press-talk trunk is a communication system receives press-talk signals from voice terminals having press-talk switches. In one aspect of the invention, the press-talk trunk is scanned by a central controller that selects an active press-talk signal and sets up a corresponding 1.times.N voice communication path among the terminals. In another aspect of the invention, the press-talk truck itself selects an active press-talk signal and notifies the central controller by means of an interrupt. In yet another aspect of the invention, the press-talk trunk also receives voice signals from all the terminals, selects a voice signal from a terminal having an active press-talk signal, and sends that voice signal back to all the other terminals. In still another aspect of the invention, two or more press-talk trunks are cascaded.

Abstract: A one-touch dial apparatus and method for registering dialing numbers in a telephone system includes a memory module divided into a plurality of memory blocks, each memory block having a number of memory locations, wherein each of the memory blocks is arranged for each of the corresponding telephones. When an intercom number for a subject telephone is generated from a source telephone, a memory block corresponding to the subject telephone having the intercom number is selected and each of the memory locations in the selected memory block is addressed sequentially. And then, a memory button is assigned to an addressed memory location and a dialing number is registered into the addressed memory location assigned to the memory button.

Abstract: An apparatus for providing an intercom function on a telephone, without the need for an external power supply, having DTMF or pulse capabilities including an intercom operation device arranged for connection to a DTMF or pulse telephone line and to a DTMF or pulse telephone instrument. The apparatus includes a device for sensing an extension selection dual input from the DTMF or pulse telephone instrument and transmitting a corresponding extension address signal over the DTMF or pulse telephone line. Also included is an apparatus for sensing a received extension address signal from the telephone line, determining whether it corresponds to the telephone instrument to which the intercom operation apparatus is connected and, upon determination of correspondence, providing an extension selection ring output.

Abstract: A signal distribution and communication arrangement includes an electronic processor-based master control unit which controls the broadcast of different types of signals through speakers located in various zones. The system includes a telephone interfaced with a door speaker controller to allow communication between the telephone and a door speaker. A page may be broadcast over the speakers and subsequently muted to allow private communication when the page is answered. Also included is a doorbell interface circuit that responds to a doorbell source. The doorbell source may be activated by any one of a plurality of doorbell switches.

Abstract: An automatic door answering and message system is disclosed. A preferred embodiment of the system has an interior unit and an exterior unit that communicate via an RF link. The system uses voice recognition and synthesis to interact with visitors. In addition to playing messages to and recording messages from visitors, the system also broadcasts to the inside their responses to predetermined queries, thereby permitting a resident to screen visitors in secret. Programmed dialogue scripts control the automated interaction between the machine and visitors. The system also has an intercom feature that enables the resident to talk with a visitor without opening the door. When the intercom is turned on, any automated dialogue script is interrupted. The system also includes a sensing means for sensing the open/closed state of the door, so that any automated dialogue script is interrupted by the opening of the door. Other embodiments include a telephone interface and a proximity sensor.

Abstract: An intercom system (110) for a drive-in restaurant (102) is integrated with a point of sale system (118) through a computer (126) that provides for tracking and managing intercom calls to operators taking orders. The computer indicates to point of sale system when a call from an intercom extension is received, and the point of sale system indicates on a terminal (116) for the point of sale system that a call is waiting. In addition to providing an interface between the intercom system and point of sale system, the computer queues unanswered calls and tracks calls after they have been answered. The computer also maintains timing of calls to assist in management of the restaurant.

Abstract: Radio and workstation nodes are operated together in a network which may be either a LAN or a WAN network. The audio is sampled from up to 16 voice sources (radios or intercoms) at a 125 micro second rate and converted into a 16-bit representation by the A-D converters associated with a digital signal processor (DSP) at the radio or voice node. The samples are then captured by the DSP and processed by the voice sampler. When the DSP voice detection software notices a signal which meets the voice detection criteria, a process is started which collects audio sample packets and continues to run as long as the voice detection criteria on a specific channel are met. These audio sample packets are assigned sequence tags and placed into a user datagram protocol (UDP) message addressed to the receiving DSP by the voice distribution process. The network protocols for UDP packets provide delivery to the correct DSP.

Abstract: A telephone station instrument add-on control subsystem with selectable addressing and ringing response delay techniques enhances any conventional instrument by providing added functionalities to ordinary telephone subscribers. When one or more of this enhanced station instruments are used on the same telephone line, a distributed single line PABX is formed. The formation of this system is based on the continuity of a pair of ordinary telephone wires. The specific routing of this wire pair does not affect the characteristics of the service features. A special case of this distributed system is to provide local dialed intercom services for communications among locations within an isolated area. A simplified version of this invention can be applied to improve the efficiency of data communication in a Local Area Network whose terminal information speed is comparable to the channel bandwidth of the transmission medium.

Abstract: A transparent telephony system is disclosed for providing hands-free communication. The transparent telephony system includes a device for initiating a call between a caller's location and a call destination based on a voice utterance (e.g., the call recipient's name) made by the caller, a device for reproducing the voice utterance made by the caller at the call destination so that the call recipient may identify the caller, and a device for handling the call attempt in accordance with a voice utterance made by the call recipient. The call handling device enables the call recipient to optionally accept the initiated call and establish two-way voice communication with the caller by uttering an appropriate voice command ( e.g., "go-ahead" or "yes").

Abstract: An integrated telephone system is provided, having a connection to a Central Office (CO) line and a connection to at least one secondary line. The CO line and/or the secondary line may be selectively accessed for two-way communication independently of each other and may be signalled for call waiting, call holding, and busy fuction. The accessing and selection are operative through a single subscriber telephone instrument. The entire system circuits are mounted on a single circuit board having pins for connection to common bus for combined use with a plurality of similarly constructed systems assigned to individual subscribers.

Abstract: The telephone system of the present invention is realized by a unique dynamic time slice architecture which allows for up to 480 transfers of data. A dual port RAM is utilized in which are stored two pages of data, containing time slice information identifying the sending and receiving devices for each time slice slot within the frame. The time slice configuration can be easily modified to accommodate a change in the current system configuration, for example, a handset connecting or disconnecting from a central office line, or the initiation of a conference call. The time slice configuration is modified by updating the second page and swapping the two pages at the beginning of the next frame so that the time slice controller accesses the second page and the configurations specified therein. Thus the system can be updated and controlled in real time with no delays to the users of the telephone system.

Abstract: A calling signal controller in which a calling signal generator having a necessary and minimum output capacity is used to the most efficiently possible extent. The controller includes a phase number memory specifying the total number of phases of calling signals used to selectively call a plurality of telephone sets, a ringing count memory loaded with a ring count for each of the phases, and a ringing control memory of which addresses are associated with the phase numbers and the ringing counts, thereby controlling the calling signals.

Abstract: A person to whom a telephone call is directed is called at an extension either by voice only or by voice during each silent period of an audible ringing signal. A plurality of telephone sets are provided where each telephone set includes a receiver for receiving a telephone call and a called person signal representative of a called person to whom the telephone call is directed. A telephone call and the corresponding called person signal can be transferred to another telephone set by placing the caller on hold and accessing a base unit which transmits the call and the corresponding called person signal to the appropriate portable unit. Each unit in the system includes a voice signal amplifier and an audible ringing signal generating circuit to output the ringing and voice calls through a speaker.

Abstract: A key telephone system with a re-dialing feature has a memory with two memory areas. One of the two memory areas is provided for an outside-line call, and the other is provided for an internal-line call to a particular extension. Each memory area memorizes a dialed number therein and replaces a number of the last intended call, previously present in the memory area, with the most recently dialed number. A re-dialing push-button automatically retrieves the number of a last intended outside-line call, memorized in the outside-line memory area, when actuated following a selection of an outside-line call, or the number of a last intended inside-line call to a particular extension, memorized in the extension memory area, when actuated following a selection of an internal-line call to a particular extension.

Abstract: The present invention relates to a key telephone apparatus. In accordance with the present invention, a port for connecting terminal devices comprises two pairs having four wires, one pair having two wires of which is connected to a digital terminal device and the other pair having two wires of which is simultaneously connected to an analog terminal device, and there is provided switching control means for automatically selecting either of an interface circuit for analog terminal device and an interface circuit for digital terminal device connected to this port in accordance with the state of use of terminal devices. Therefore, it is possible to connect a one-pair two-wire analog terminal device and a one-pair two-wire digital terminal device together to one port and select either the interface circuit for analog terminal device or the interface circuit for digital terminal device according to the state of use of terminal devices under surveillance of the switching control means.

Abstract: A key telephone system, having ports for connection to telephone lines of a telephone exchange and ports for connection of terminal apparatus including key telephone sets, is provided with the ability to distinguish if an intended call or feature access involves more than the key telephone system. If so, a signalling protocol of the telephone exchange is emulated on behalf of the terminal apparatus and transmitted via one of the telephone lines whereby the progress of the call or feature access continues, as if a user of the terminal apparatus had initiated the signalling protocol of the telephone exchange.

Abstract: The invention relates to an intercom system comprising a central unit and several remote stations connected by two-way lines to the central unit into a star network, whereby the lines are selectively interconnectable via the central unit for establishing a connection between desired remote stations. The number of simultaneous connections can be increased and the speech signals can be more reliably passed to the right remote stations when the two signal directions of each line are separated from each other at the central unit and the connection is established by connecting each signal direction separately.

Abstract: Several ISDN telephone terminals in a passive bus configuration are enabled to be used to share a single voice communication in the familiar extension phone arrangement by means of a second bus connecting the analog sides of the terminal circuits. Once an incoming or outgoing voice call has been established at one of the number of ISDN terminals located on the premises, any others of such terminals may join the conversation by simply completing an off-hook connection by way of the analog bus. In conversion of premises to ISDN systems, the abandoned conventional telephone wiring may be employed as the analog bus. Conventional analog phones may also be utilized with ISDN voice terminals via the analog bus.

Abstract: An intercom system for use in combination with a multi-line telephone system wherein the intercom system utilizes the same wire pair for communications between intercom units that is used for normal telephone communications. The intercom system transmits voice signals on two or more frequency modulated channels over a wire pair of a local telephone network. Each intercom unit includes a microprocessor which controls communication activity and protocol in each unit and communicates with other intercom unit miroprocessors via a separate frequency modulated digital signal channel.

Abstract: An intercom system for use with a plurality of telephones on a single extension includes a single master station and a plurality of slave stations. The master station is connected so as to interrupt the telephone line pair to and from a central exchange. Each slave station is preferably associated with a handset that is on the extension. When the extension is not being used for intercom service or for an outside call, any telephone handset on the extension that has a keypad can initiate a signal that is received and decoded in the master unit. When the master station receives such a signal, it disconnects the line to the telephone exchange from the extension and connects the telephone exchange to a circuit that detects incoming calls so that they can be signaled to users. The master station also sends a signal to each slave station that enables the intercom function.

Abstract: A communication system for use with a single pair of externally provided telephone wires and a single pair of in-house wires for the provision of full intercom services and/or PABX type features to a plurality of subsets includes a line interface module connected between the single pair of externally supplied wires and a single pair of in-house wires. In addition, each subset is provided with a station adapter module between it and the single pair of in-house wires.

Abstract: A gating circuit for operation in conjunction with a manual cord telephone switchboard to service multiple operational modes of a subscriber telephone connected for telephone communication to a central office. In one mode, an internal intercom connection is established between the subscriber telephone and the switchboard. In a second mode a secretarial service connection is established allowing direct communication between the switchboard and the central office. A ring detection circuit detects when the subscriber telephone has been rung from the central office.

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 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 communication system includes station sets having one or more function enable buttons and a plurality of line access buttons. The function enable buttons include the extension, transfer and send message buttons. Each line select button is associated with a communication line and with the station set associated with that line. Operation of a function enable button initiates the feature associated with that button and also changes the function of a line select button from a line access button to an auto-dial select button for dialing the station associated with the line select button.

Abstract: A cordless telephone having a base unit and a separate handset unit is operable in an intercom mode in which operators at the two units are in telephonic communication. If an incoming telephone call appears when the telephone is in the intercom mode, the loudspeaker of the handset unit and a ringer of the base unit both produce a ringing sound to announce the call. When one unit is then disabled by the operator thereof hanging up, the other unit is automatically connected to the telephone network line to receive the incoming call. The handset unit produces the ringing sound from its loudspeaker at a first volume when it is disabled and in a standby mode, and at a second lesser volume when it is enabled and in the intercom mode to avoid producing a loud ringing sound directly into the ear of the handset operator.

Abstract: A cordless telephone has a transfer capability by which an incoming telephone call may be transferred from the base unit to the handset unit or from the handset unit to the base unit. Each unit includes an intercom key which may be actuated to place the telephone in an intercom mode wherein the base unit and the handset unit are in communication with each other while the incoming call is on hold. Deactuation of one unit in the intercom mode results in the other unit being automatically adapted to receive the incoming call. Alternatively, actuation of either intercom during the intercom mode results in both units being automatically adapted to receive the incoming call and placed in communication with each other.

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: An in-line intercom system for use with telephones, in particular, a single line telephone. The intercom system includes an intercom unit, a hold unit and a ring silencing unit. The system is electro-mechanical and is modular so that it can be inserted directly into most existing telephone lines.