Abstract: A communication system of the present invention includes an exchange connected to a plurality of subscriber terminals. The exchange includes a display data management section which includes first and second tables. The first table indicates types of messages and is used to refer to the second table. The second table stores data of display messages classified for individual message types and is retrieved with a message number. When a calling party depresses a message displaying function key and then depresses a message number on a subscriber terminal, the exchange recognizes that a message display request has been input. The exchange reads out data associated with the display message from the display data management section, and causes a terminal display section of the calling party terminal to display the data and further causes a terminal loudspeaker section to output speech to allow the calling party to confirm the display message.

Abstract: The invention relates to a method whereby a communication apparatus, advantageously a portable telephone, is set in a keyboard lock mode (130). The communication apparatus comprises a call terminating key, which is used according to the invention so that a short depression thereof only terminates the call (110), but a press-and-hold function, or pressing the key twice in succession or first pressing and then waiting for a given delay (120) sets the apparatus in the keyboard lock mode (130). The invention also relates to a communication apparatus for applying the said method.

Abstract: A method and system of providing telephone service comprises associating a list of telephone numbers with a representative telephone number. A call to the representative telephone number is detected and a plurality of telephone numbers on the list are simultaneously signalled. Thereafter, signalling is terminated at at least one of the plurality of telephone numbers thereby allowing a connection to be established with one or more parties at telephone numbers among the plurality of telephone numbers. Each telephone number on the list may be a representative number which is associated with another list of telephone numbers.

Abstract: A service for screening outgoing telephone calls. The service allows a subscriber to determine the times of day and/or days of the week when she wants her outgoing calls on her telephone line to be restricted to numbers which have been approved by her. Calls to numbers other than those on the authorized list will not be completed. Incoming calls are also restricted and a privileged caller code must be entered for the outside caller to complete the call to the subscriber.

Abstract: A system and method for utilizing a common channel signaling network controlling a communications system to detect predetermined events and to execute a predetermined script upon detection of those events. This is accomplished using the common channel signaling network in conjunction with programmable and addressable monitors coupled to the common channel signaling links connected to the signaling transfer points (STPs) . These monitors are programmed to trap and temporarily record predetermined data associated with specific events which it is desired to memoralize. The monitors provide an output to a control processor having an SSP capability which is linked to the STPs. The monitors are programmed either through the common channel signaling network or through a monitor port connected to the control processor to collect data including the identities of called and calling stations and data from which the duration of connection of the call may be determined.

Abstract: A method and corresponding apparatus utilizes questioning to provide secure access control including the steps of storing information in a database; generating at least one question based upon the information stored in the data base; communicating to the user the generated question(s); receiving a response associated with the question(s), interpreting the response to determine whether the response conforms to the information upon which is based the associated question(s); and outputting an authorization status indicating whether or not the user is authorized for access according to the determination. The question(s) concerns a relationship among portions of information contained in said data base. This feature is advantageous because it protects against an eavesdropper gaining access to the service or facility and provides the capability of generating a relatively large number of different questions from a small data base.

Abstract: A current detector for connection in series with a lead carrying current to be detected, has a first branch with a plurality of series connected diodes having an anode end and a cathode end for connection to the lead, a first optocoupler light emitting diode connected in series with a resistor, connected in parallel with the first branch, the optocoupler diode being connected in the same polarity direction as the diodes in the first branch, and a first further diode connected in parallel with the first branch, in opposite polarity direction as the diodes in the first branch.

Abstract: A logical network is defined by a plurality of restricted class telephones in which such telephones incorporate a network access code characterizing the logical network. Each telephone contains a verification device that allows each telephone of such logical network to verify that others of such telephones are members of that logical network by transmission and receipt of a network access code. The logical network is useable on any telephone system, including public telephone service networks, cellular telephone systems and radio telephone systems. The verification device may be installed as a retroactive addition to the standard components found within existing cellular telephones or may be included as part of the technical design in new cellular telephones.

Abstract: A communications system is designed to exempt communications services users, such as wireless communications subscribers and calling card callers, from entering an authentication code for calls directed to pre-selected destination numbers, notwithstanding the authentication code entry requirement implemented by the communications services provider for all other calls.

Abstract: A remote access call forwarding method and system adapted for an Advanced Intelligent Network to forward a call incoming to a subscriber's telephone number in response to a routing destination number if the routing destination number does not correspond to a blocked destination identifier retrieved from a database. Further, a search to a subscriber profile unique to each subscriber is provided, the subscriber profile containing valid routing destination numbers previously validated to which the calls incoming to the subscriber have previously been forwarded. Thus, calls are forwarded in response to the routing destination number when the routing destination number matches a valid destination number found in the subscriber profile.

Abstract: A transparent telephone access system using voice authorization includes a method and system (30 and 60) to protect against the unauthorized use of telephone network (20). By receiving a spoken telephone number (14) from telephone unit (16) and recognizing the spoken phrase that corresponds to telephone number (24), the method and system permit transmission through telephone network (20) to telephone (22). The method and system record spoken phrase (14) in voice recognition server system (18). For the spoken phrase, a voice-template is formed and compared with a voice template formed from a composed phrase including pre-existing or stored spoken digits. In response to the comparison, use of telephone system (16) through telephone network (20) is permitted.

Abstract: Encumbrances on making calls charged to a card can be reduced by a) storing information so that an association is created relating a card number and at least one calling telephone station, from which card calls charged to the associated card are to be made, b) using the association to retrieve the card number at the time a card call is made from the at least one associated telephone station and c) automatically supplying the retrieved card number to the telephone network at the appropriate part of call set-up, so that the card number need not be entered by the calling party. The association between the card number and the telephone station, which may be referred to as a "logical link", is 1) independent of any pre-existing relationship between the card number, or any subset thereof, and the telephone number of the telephone station and 2) continues to exist despite the going on hook of the calling telephone station.

Abstract: A method of receiving concentrated calls enables a specific terminal of an exchange of a communication network to receive concentrated calls from callers without letting the callers repeat the calls. The method registers calls to the terminal during the congestion of the exchange. Once the congestion is dissolved, the method connects the terminal to the callers one after another. The method prepares a registration list and a reception list in the exchange. In response to a request from the terminal, the exchange stores reception conditions of calls such as a reception time and the number of calls to receive in the registration list. Upon receiving a call from a caller to the terminal, the exchange determines whether or not the call satisfies the reception conditions without connecting the call to the terminal. If the call satisfies the reception conditions, the exchange records the number of the caller, etc., in the reception list and terminates the communication with the caller.

Abstract: A method and apparatus for managing institutional telephone activity utilizes a computer control unit to control a trunk management unit, which connects institutional telephones to outside telephone lines. The computer control unit contains a database for storing the calling privileges and restrictions of institutional users and for recording calling transactions made by the users. The computer control unit implements a prospective call screening feature whereby outside recipients of undesired calls from the institution may enter a code that directs the computer control unit to prohibit similar calls in the future.

Abstract: A cordless telephone system comprises a base unit and a portable handset having a rechargeable battery. To conserve battery power in the handset, the ringer is normally in an inactive state but may be switched active for a predetermined period of time. Thus, if the handset is within the range of other telephones within a household, the ringer on the handset will normally not be activate and the ringer on the handset will not indicate the receipt of an incoming call. To activate the ringer for the predetermined period of time, which would be desired when the handset is out of range of the other telephones, the user presses a timer switch for activating a timer. A CPU in the handset then enables the ringer while the timer is counting down the predetermined period of time. In another embodiment, the user can enter a desired period of time during which the ringer is active.

Abstract: There is provided computerized method of enrollment in a computerized system and the verification of the location of employees. Each employee, using a predetermined set of instructions, telephones a computer which, under the control of a program and a voice recognition and speech identification device, derives a voice print of the employee. When the employee is sent to a location, the ANI and voice print, which are in the computer's database, are verified. If the correct telephone is used, and the voice print compares, the time and place of the telephone call and the employee are recorded for later use by the employer.

Abstract: An operations facility is provided for administering unsubscribed telephone lines and conserving the use of the phone numbers associated with such lines by associating a plurality of unsubscribed lines with the same telephone number and same switch line termination point. Advantageously, then, a plurality of unsubscribed lines may be inexpensively provisioned with soft dial tone, thereby allowing a potential telephone subscriber to interactively subscribe to and activate telephone service from an unsubscribed line. Moreover, the application of soft dial tone may be used to identify a network access endpoint that is being used by a customer, and thus improve the accuracy of the contents of databases used by the operations facility in the provisioning of telephone service by identifying incorrect data.

Abstract: A device for detecting an operation state of a telephone hook switch in a telephone includes a timer, a controlling circuit, a counter and a table electrically interconnected. According to the present invention, the abnormal signals generated by the hook switch cannot be accepted by an exchange or even if the signals are accepted by the exchanger, the mute function of the telephone will be utilized to make the users unable to listen to each other.

Abstract: The use of subscriber identifiers in a voice directed telecommunications system employing automatic speaker recognition is enhanced such that a group of subscribers may share the same identifier.

Abstract: A method for controlling telephone fraud of the type whereby a caller places calls or accesses services via unauthorized use of a credit card number or other authorization number. For such control, an initial call using the number and meeting a certain primary criterion (such as placement to a geographical area known to receive numerous fraudulent calls) is intercepted and it is determined whether or not that call is an authentic use of the number. If authentic, other calls are then allowed without interception, even though they may meet the primary criterion, unless or until a secondary criterion is met. Meeting the secondary criterion (which may relate to calling patterns indicative of fraud) also causes a call to be intercepted and a determination made as to whether the use is authentic. For interception due to either criterion, if the call is determined to be inauthentic, the authorization number may be removed from service.

Abstract: Relates to arrangements for utilizing an originating caller's customer network identifier (ONI) to provide special treatment of a call, especially one that terminates outside the caller's network. The ONI is recognized in an originating switching system and is transmitted in an initial address message (IAM) to the terminating switching system for serving the call. In the terminating switching system, the ONI is used to screen the call for special treatment such as denied termination, denied termination for collect calls, or direct completion to a principal of a principal-secretary group. The ONI is also used for screening for use of originating services for members of a network. The originating or terminating switch can also query a data base to obtain screening data.

Abstract: A distributed computer system employs certificate based alias detection to ensure a policy of separation of duties. Biometric information is collected during computer user account creation that is converted to canonical form and digitized. This digitized canonical form, along with account data and authentication data, is included in the user's account information. Authorization to execute any task is validated at the time a request is made by comparison of the digitized canonical forms of biometric data of the user completing the request with those of the user initiating the request.

Abstract: Methods and apparatus are disclosed for providing increased security in a telecommunications network by using quasi-time domain reflectometry techniques to identify those telephone calls which comprise multiple legs. Echo data are collected for the telephone call from a predetermined point in the network to a point where the call originated. The data are processed to generate an indication of whether the telephone call comprises multiple legs, thus identifying those calls most susceptible to unauthorized use. The indication that a telephone call comprises multiple legs is advantageously used together with call attribute information, such as whether the call is placed to an international destination, to determine whether a given multiple-leg call is most likely a valid access to the communication system or most likely fraudulent.

Abstract: An apparatus for restricting telephone calls. The apparatus is wall mountable and can be powered by power available from a telephone line equipping a facility. Visually, the device emulates the appearance of a standard in-wall telephone connector package, with the electrical components of the device concealed with the facility wall. A programmable processor is incorporated into the apparatus allowing the user to override restrictions, enter new restrictions, or change the security code through entry of digits from a standard tone or pulse dialing telephone. Use of linear logic protocol in programming reduces complexity of programming and probability of error. The device temporarily disconnects the telephone from the network as each programming sequence is completed, preventing a tie-up of the network and reducing the probability of an accidental establishment of a local or long-distance connection.

Abstract: A telecommunications system allows multiple users to place and charge telephone calls to personal debit accounts without requiring specially designed telephones or "smart" cards. The system keeps track of the cost of each call, including applicable taxes, in real time and notifies the user when the account balance approaches zero. The system allows the user to restore the account balance in real time either manually or automatically by charging the increase to a commercial credit card. The system has multiple interactive call management subsystems, each subsystem having its own database. When one database in one subsystem is updated, signals are transmitted between subsystems to update every other database. An account in use flag is transmitted from a serving subsystem through a network to each of the other subsystems to prevent simultaneous use of an account.

Abstract: An apparatus and method for automating the processing of foreign collect calls to U.S. telephone numbers. By automating the check of the U.S. telephone number against the pay telephone numbers and other non-billable numbers in U.S. databases, the amount of foreign operator effort required is reduced. The apparatus and method also reduces the losses to U.S. telephone companies due to foreign collect call processing errors and foreign collect calls fraudulently completed to pay telephones or other non-billable telephone numbers.

Abstract: A telephone apparatus including a decoder, a memory, a comparison circuit and an output device. The decoder serves to detect and decode telephone number information of a calling side transmitted with bell signals through a telephone line. The memory stores telephone number data of calling sides in correspondence with operation keys. When a call is received, the comparison circuit compares the output data of the decoder with the telephone number data stored in the memory. If a coincidence is detected between the output data of the decoder and the telephone number data of the memory based on the comparison result of the comparison circuit, the output device notifies a user that the call corresponds to one of the telephone number data stored in the memory. The output device includes indication units provided in correspondence with a plurality of operation keys, and a driving control circuit for selectively activating the indication unit of the operation key corresponding to the coincident telephone number data.

Abstract: A system detects unauthorized use of an identifier in a communication system which includes at least one terminal coupled to a communication center via a communication network. The system includes a first part provided in the communication center for managing a password and a previous caller telephone number in correspondence with each identifier, and a second part provided in the communication center for sending a warning message to the terminal if an access identifier and an access password input from the terminal from which an access request is made respectively match one of the identifiers and a corresponding password managed by the first means but a present caller telephone number from which the access request is made is different from the previous caller telephone number.

Abstract: A unified and systematic approach is taken both to design of a virtual communications network within a carrier's telecommunications network, and to design the screening filters provided in the VCN data base which control the admission of calls to the network. For this purpose, telecommunications traffic information that is relevant for both the design of the VCN architecture as well as for development of the screening filters is aggregated and applied both to a network design tool that is used to generate the customer's virtual network configuration, as well as to a screening filter generator (SFG). The traffic information may include, for example, traffic data contained in network and customer premises equipment call detail records and billing data.

Abstract: A dialed number recorder, a data monitor, and a personal computer are connected in combination to monitor the data traffic on a suspect "hacker's" telephone line. At the beginning of a call, the dialed number recorder receives and interprets the DTMF signals detected on the line and translates the DTMF signals into the corresponding telephone number dialed. The data monitor receives all signals on the line and converts them into their corresponding characters and transmits these characters, to the personal computer where the characters are stored in a buffer in dynamic memory. The personal computer compares the received data stream against a set of known characters strings looking for a match. If an on-hook signal (indicating the end of the call) is received without a match, the data stored in dynamic memory thus far is erased. If any series of sequential characters matches one of the known strings, the buffered data is written to the computer's disk.

Abstract: In caller ID telephone service system, if a calling party does not want to display his telephone number on the called party side, the calling party takes an authorized key number (hereinafter called "blocking key number") with the telephone exchange office. The key number is composed of a 3 or 4 digit numerical signal, like a push-phone tone, when the subscriber calls any subscriber (called party) telephone number in this service area. If he dials that key number first and then the conventional number, the telephone exchange office detects that key number, then blocks (stops) sending the calling party telephone number to the called party side. On the other hand, the called party side has a device with a relay which functions to take out the associated telephone set from the telephone line after one ring because the device cannot detect telephone number information between the first ring and second ring.

Abstract: An automatic answering telephone set comprises a voice synthesizing unit and a voice detector for reproducing a recorded message in response to a remote control performed by using a predetermined password number. A plurality of decoy numerals are inserted immediately before each of numerals constituting the preestablished password number to thereby form a pseudo-password number including the decoy numerals. A calling party is inquired of with the pseudo-password number. An input password number is then formed in accordance with replies of the calling party as detected by the voice detector. Only when coincidence is found between the predetermined password number and the input numerical password, the remote control is accepted.

Abstract: A circuit which prevents a telephone or a plurality of telephones from making unauthorized or restricted calls to specific numbers or unspecific groups of numbers. The restricted call numbers may be local or toll call. The circuit is disabled either on a call by call basis, or indefinitely by entering a user defined pass code. The circuit is programmable from any commercially available touch-tone phone. When in the call restriction mode, the circuit detects outgoing calls by detecting and decoding standard `DTMF` burst. Upon detecting the first valid tone, the circuit isolates the user from the central office equipment. The circuit then parses the first and all following DTMF bursts and compares them against preprogrammed internal lists of fixed or relative restricted numbers.

Abstract: Data communication apparatus which dials based on the preregistered telephone numbers, prohibits or allow data communication based on the telephone number data the apparatus includes a memory to memorize the data for judging if data communication is allowed for a telephone number an a control to control dialing based on the result of such judgment.

Abstract: A telephone security device is placed in the telephone line between the primary transmission network and receiver. Incoming telephone calls are automatically answered and monitored for a predetermined time. When a proper code is supplied by the calling party during the monitored time interval, an audio alert is sounded so the called party may pick up the phone and responsd in a normal manner. If the phone is not picked up during the time interval, the call is terminated.

Abstract: A method for facilitating call completions utilizing a call identification telephone number which is transmitted along with an incoming call. A user of the call processor of the invention can program a list of anticipated or preferred call identification telephone numbers, together with destinations to which it is desired to route the respective incoming calls. During an incoming call, the call processor matches the associated call identification telephone number with a preprogrammed number and thereby completes the call according to the programmed destination.

Abstract: A call processing embodiment where customers are offered, in addition to the conventional office dialing plan, a special dialing plan where received numbers are processed such that a query of a database is defined when a prespecified access code, e.g., *66, is received, for example followed by a destination number, but where call blocking is defined for a predefined plurality of destination numbers, e.g., all destination numbers beginning with 976 or 1-900 or all destination numbers beginning with 1, when such numbers are received without the prespecified access code. Illustratively, the database query may result in the customer being prompted for a personal identification number (PIN) and accordingly 976 or 1-900 access is thereby limited to those knowing the PIN. The database may perform other call screening and call management operations such as time of day or day of week screening or limiting the number or cost of 976 calls in a given time period.

Abstract: A timing circuit and apparatus that utilizes this circuit. The apparatus is particularly suited for use with a telephone network interface, for substantially preventing a third party who gains access to the interface from placing an unauthorized telephone call through a network connection obtained through a jack, typically modular, located in a customer portion of the interface. Specifically, this apparatus is connected in series within the telephone company side of the interface to illustratively a ring lead of an incoming subscriber loop. In operation, the apparatus provides network access, by supplying loop current, on a timed periodic (repetitive) basis to a telephone (or other equipment through which a telephone call can be placed) plugged into the jack located within the network interface. Access is provided for a period of time that is sufficient to test loop current but is insufficient to allow the network to complete a call dialed from that telephone over this loop.

Abstract: Disclosed in an apparatus and method for effecting timed-do-not-disturb services in telephone networks. An adjunct computer is associated with the Remote Memory Administration System (RMAS) for switches which include a facility for providing call forwarding services. The adjunct computer is inserted between the RMAS and the switches which it controls. The adjunct includes a processor responsive to subscriber identification and stored class of service information to recognize that timed-do-not-disturb service is to be provided to an identified subscriber station. The processor receives requests for timed-to-not-disturb service via a multiline hunt group associated with a do-not-disturb access number associated with a voice response unit which feeds request signals to the processor and voice prompts to the caller.

Abstract: A telephone line access control or call-barring unit operates on the monitor-and-clear principle to achieve selective call barring. The unit monitors dialled pulses being sent to an exchange, and recognizes a four-digit security number or authorization code intended to be known only to authorized users for bypassing the call-barring function. It also recognizes one or more two-digit or three-digit access codes for programming the call-barring unit to enter various different call-barring modes. The programmablity is purely in response to dialled numbers from any telephone connected to that particular line, and includes the option of changing the authorization code.

Abstract: A call screening device is disclosed for use with a telephone system including one or more telephones connected to outside telephone service in order to screen incoming call signals directed to the telephone system and for providing, in response to a preselected security code signal, the incoming call signals to the telephones. The call screening device includes circuitry for storing the preselected security code signal and for receiving the incoming call signal and an incoming code signal from the outside telephone service. Circuitry is provided for comparing the incoming code signal with the preselected security code signal and for providing the call signal to one or more telephones when the comparing circuitry determines the incoming code signal corresponds to the preselected security code signal. The device may be activated or deactivated in response to a preselected control signal from any of the telephones.

Abstract: An inexpensive, reliable telephone answering device screens out undesirable calls, screens the calls that are dialed out and inhibits preprogrammed call prefixes from being dialed, adds the "hold" function and a simulated call transfer function to all telephones (activated by depressing a TOUCH TONE key on a standard telephone set), provides a way to use the telephones in the home as an intercom system, and provides other advanced PBX functions at low cost in a home or small business environment. A power off failsafe feature prevents power loss to the device from interrupting normal telephone operation. Several caller access codes and several dial inhibit codes can be programmed from a conventional unmodified subscriber Touch Tone telephone set, and a personal access code prevents system programming from being changed by unauthorized persons or accidentally.

Abstract: According to the invention, between the two wires (A and B) of the line, an active dipole (DA) is inserted capable of having a low or high impedance. This dipole includes an operational amplifier (AMP) whose output (2) makes it possible to analyze dialling attempts.

Abstract: Disclosed is a method and apparatus for detecting a fraudulent toll telephone call made by a device coupled to a telephone, which device can generate a single-frequency (SF) tone control signal and multi-frequency (MF) signals used in a toll telephone network. The method comprises the steps of, (a) identifying an off-hook condition on a toll analog SF trunk line by detecting loop current on the trunk, and (b) detecting on the trunk an SF tone control signal indicating an on hook condition, followed by a predetermined number of MF control signals. The fraudulent call can be cancelled by actuating a relay having contacts in at least one control lead of the SF trunk.

Abstract: An apparatus for restricting outgoing telephone calls 10 includes field effect transistors 501, 502, 503, 504 and 505 connected to telephone lines 11 and 12 in a nonpolar configuration. Signal conditioners dual tone multifrequency integrated circuit decoder 301 and operational amplifier 302 are connected to the MPTs. The outputs of dual tone multifrequency integrated circuit decoder 301 and off amp 302 are directed to microprocessor and piggyback ROM combination 101. Microprocessor and piggyback ROM 101 analyze, store and compare subsequent dialed telephone numbers to restrict particular outgoing calls. Microprocessor and piggyback ROM combination 101 is configured to allow or disallow a particular telephone number based upon an area code, and/or the local office exchange code and/or the particular four-digit customer number.

Abstract: A phone screen security system for blocking unwanted incoming phone calls and unauthorized outgoing phone calls includes a ringer pick up circuit which is actuated by a conventional ring signal of an incoming call on an outside phone line. The ringer pick up circuit actuates a voice synthesizer which requests a caller to input a security code. The input tone signal is transmitted to a code detect circuit which compares the input signal with a preprogammed security code. A timing circuit is connected to the code detect circuit and the ringer pick up circuit for disconnecting the outside phone line after a predetermined time interval if a correct security code is not detected. If a caller inputs the correct security code, the voice synthesizer is actuated to inform the caller. If an incorrect security code is input, the caller is disconnected. The code detect circuit connects the incoming call to a lines select relay if the correct security code is entered.

Abstract: A system for selectively receiving incoming telephone calls to a phoneset includes an automatic answering device which answers all incoming calls by placing a simulated phone load across the phone lines. The answering device also enables a dual tone multifrequency (DTMF) receiver to receive tone frequencies input by a caller. The DTMF receiver decodes the tone pulses into binary coded decimal values which are stored in successive storage registers. A comparator compares the values stored in the registers with a respective code input by the subscriber and outputs a signal when the code dialed in by the caller matches the code input by the subscriber. The signal activates an electronic ringer circuit which serves to alert the subscriber of the presence of an authorized call. An off-hook detector detects the pick-up of a phoneset by the subscriber and acts to disable the electronic ringer circuit.

Abstract: A telephone lock unit having two selectable locking modes will limit (a) all long distance and operator cell connections or (b) all local, long distance and operator call connections to all persons other then those implementing the correct access code onto the telephone dial or keypad. The unit operates in conjunction with conventional pulse and tone dialing type telephones while being of a self contained electronic design. The access code which may contain 3 or 4 digits can be programmed by any authorized person by means of an internal matrix switch. A save and relock function allows any authorized person knowing the correct save and relock code the option of disabling and reinstating the locking mode function. The locking mode functions are performed electrically by momentarily disconnecting the telephone from the telephone line causing the re-occurrence of the dial tone, thus canceling all previous call atempts.

Abstract: A device for screening unwanted telephone calls is connectable at a station etween a telephone set and a wall outlet plug. In response to ringing current received at the station and signaling an incoming call, the device delays audible ringing at the station for a 2.5 second period. During such period, the call's sender transmits to the station a # dial signal only if the call is in a special category as, say one undertaken to try to make a sale. If such # signal is received during such period, the device transmits back to the sender a return signal acknowledging that the call has been received and rejected at the station, and the device then hangs up call at the station without any audible ringing taking place there. If no such # signal is so received, audible ringing occurs at the line upon expiration of such period, and the call continues in its normal sequence.

Abstract: A system for selectively receiving incoming telephone calls to a phoneset includes an automatic answering device which answers all incoming calls by placing a simulated phone load across the phone lines. The answering device also enables a dual tone multifrequency (DTMF) receiver to receive tone frequencies input by a caller. The DTMF receiver decodes the tone pulses into binary coded decimal values which are stored in successive storage registers. A comparator compares the values stored in the registers with a respective code input by the subscriber and outputs a signal when the code dialed in by the caller matches the code input by the subscriber. The signal activates an electronic ringer circuit which serves to alert the subscriber of the presence of an authorized call. An off-hook detector detects the pick-up of a phoneset by the subscriber and acts to disable the electronic ringer circuit.