Abstract: A method of improving the CAS (customer premises equipment alert signal) tone signal detection of a telephone which uses a CAS tone signal detection chip or data signal processor in the telephone to detect a small segment of the CAS tone signal received from the exchange line and to trigger a CPU in producing an interruption signal, causing the telephone to mute the voice signal from the near end subscriber and to detect and judge the time series of the left CAS tone signal, and uses a voice signal detection circuit to monitor the voice signal from the far end subscriber, so that the telephone accurately measures the length of the CAS tone signal when no voice signal from the far end subscriber or the near end subscriber is detected, and judges, subject to the definition of a predetermined CAS tone signal length specification, whether the CAS tone signal is true or false.

Abstract: A method for separation of acoustical data into narrowband and broadband time series components includes the steps of: constructing a data matrix in which time series samples of acoustical data are arranged in a forward-backward linear predictor matrix; decomposing a subband of the matrix into an in-band component and an out-of-band component; estimating narrowband components; estimating out-of-band leakage; removing the in-band narrowband component and the out-of-band narrowband component; repeating sequentially the afore mentioned five steps until narrowband components from all of the subbands of the matrix are removed from the acoustical data; and reconstructing the broadband time series; whereby to provide a narrowband time series estimate indicative of the presence of a signal in the acoustical data.

Abstract: A method of generation and detection of acoustic signals carrying alpha-numeric data for reducing the effects of noise and thereby improving signal transmission without the need to boost the power of the signal. In accordance with one aspect of the invention, a special DTMF acoustic signal consisting of a combination of two frequencies will be generated for the representation of a particular alpha-numeric character that will be similar to the standard DTMF tone. The difference between the amplitudes of both frequencies varies during the time of generation of the DTMF tone in such a way that both signals will arrive at a final destination detector, i.e., an interactive voice response board, at least for a portion of the generation time, at a relatively similar amplitude, thereby substantially increasing the probabilities of being recognized as a DTMF signal.

Abstract: The present invention utilizes common hardware and software routines already present in most digital telephone devices, e.g., a DTMF detector; to download data over a telephone line to a digital telephone device. Each symbol of a numeric system, e.g., a hexadecimal system, used to represent the data is associated with a DTMF tone pair. The DTMF tone pair is downloaded from a data source such as a manufacturer of the digital telephone device, to the digital telephone device using a telephone line. Other tones may be used to provide control signals between the data source and the digital telephone device. Thus, using common and inexpensive routines in a typical digital telephone device, the expense of a modem or other conventional data communication device is not necessary to receive data.

Abstract: Apparatus and methods for adaptively, reliably, and accurately measuring the frequency of an alerting or other signaling tone. A tone detector measures the frequency of a tone (continuous or pulsed) with a high degree of accuracy (e.g., to within 1 part in 10,000). Two lower order or smaller DFTs measure the energy level in two separate but intersecting frequency ranges. A simple ratio is determined from the relative energy measured from discrete Fourier transforms relating to each of the two separate frequency ranges, and an actual measured frequency is determined.

Abstract: A method of facilitating telephony communications over a packet-switched network includes detecting signaling tones in an audio stream and blocking them from the stream in response to the detecting. After the blocking, the audio stream is sent over an undependable channel in the packet-switched network. The detected signaling tones can be sent over a dependable channel instead of the undependable audio channel.

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: Apparatus for remotely powering access equipment over a 10/100 switched Ethernet network comprises an Ethernet switch card with a phantom power supply for remote access equipment and added circuitry for automatic detection of remote equipment being connected to the network; determining whether the remote equipment is capable of accepting remote power in a non-intrusive manner; delivering the phantom power to the remote equipment over the same wire pairs that deliver the data signals, and automatically detecting if the remote equipment is removed from the network.

Abstract: A testing environment and a method for telephone number identification and/or verification. The testing environment and method of the present invention analyzes incoming analog signals of a telephone call being made to the tested line as the receiving party from the central office switch. These incoming analog signals preferably include ring signal, waiting call tone and voice signals. The incoming analog signals are analyzed and processed by the testing unit according to the present invention in order to identify and/or verify the telephone number. Thus, the testing environment and method of the present invention has the advantage of being able to analyze data received from the tested line as the receiving party, rather than requiring the tested telephone line to initiate the telephone call for testing purposes.

Abstract: A system and apparatus for enabling communications devices to recognize call progress tones that may be used in foreign countries. The call progress tone detection system includes a communications device (50) having one or more frequency decoders (113) for determining the frequency of call progress tones, a cadence decoder (126) for determining the on/off pattern for the call progress tones and a table (122) for storing the call progress tone frequencies and the cadences. Recognition of call progress tones is accomplished by enabling the communications device (50) to receive one or more foreign call progress tones, enabling the user to associate the type of call progress tone for each call progress tone received and storing each call progress tone to a table (122) for later cross reference when initiating a call.

Abstract: To determine whether a received signal represents a dual tone multi frequency (DTMF) code, a characteristic of the received signal is repeatedly measured over a period of time, thereby obtaining a plurality of parameter measurements. This may include separating the received signal into low band and high band signals and for each of the low band and high band signals, determining a plurality of squared magnitude measurements over the period of time. A deviation value is then determined for each of the plurality of parameter measurements, and an average deviation value is determined from the plurality of deviation values. The average deviation value is compared to a threshold value, thereby obtaining a comparison result. The received signal as alternatively designated as representing or not representing a DTMF code on the basis of the comparison result.

Abstract: In a communication device, a decoded audio signal is evaluated by a detection function (112). Two portions of the decoded audio signal spectrum are evaluated, a ringback band (206), and the remaining band(s). The signal strength in the ringback band is measured against a preselected ringback energy threshold level and the non-ringback signal strength is measured against a voice energy threshold level. Only if the ringback energy is above the ringback energy threshold level and the non-ringback band energy is below the voice energy threshold level will a ringback filter be applied to the audio signal.

Abstract: A multiple tone detector includes n tone detectors, each detecting one of n distinct tones, where n.gtoreq.2, and a background detector which generates a measure of accumulative background energy E.sub.avg in a frequency band or bands which do not include at least a subset of the n tones. The output of the background detector is applied to a smoothing filter, which generates the accumulative background energy measure E.sub.avg for a current frame as a weighted sum of the background detector output for the current frame and the background energy measure E.sub.avg from a previous frame. A parameter controlling response time of the smoothing filter is varied depending upon whether or not speech is determined to be present in the background portion of the input signal. A processor uses the energy measures from the n tone detectors and the background detector to compute n ratios, where a given ratio is the ratio of the energy measure of the ith tone to the accumulative background energy measure E.sub.avg.

Abstract: A system and method for modifying voice signals to avoid triggering tone detectors in a telephone network. The system includes a voice processor coupled between the handset and station set of a conventional telephone unit. The voice processor modifies the voice signal to prevent triggering DTMF tone detectors.

Abstract: A method and system for distinguishing valid DTMF signals from spurious DTMF noise includes detecting signals having a first signal component indicative of DTMF signals and having a second signal component having frequencies unrelated to DTMF frequencies. The second component is utilized in isolation from the DTMF frequencies of the first signal component. The analysis includes determining a signal level representative of the second signal component. If the signal level exceeds a predetermined threshold level, the first signal component is determined to be spurious noise. On the other hand, if the signal level is below the threshold level, the first signal component is passed to a DTMF-responsive system, such as a voicemail system or a voice response unit. Optionally, the operation includes requesting confirmation of the signal of interest, if the signal level of the second signal component falls within a range which includes the threshold level as its upper limit.

Abstract: A communications terminal apparatus capable of detecting a busy tone by measuring time periods of a periodic tone state and off-tone state is provided. The apparatus includes a data transmitter and receiver, memory for storing first and second reference time ranges, first and second timers for measuring tone and off-tone state time periods of a signal on a telephone line, respectively, and a busy tone detector. The busy detector detects a busy tone by determining whether the measured tone and off-tone state time periods are within the first and second reference time ranges, respectively, and determining whether the signal alternately includes the measured tone and off-tone time periods.

Abstract: A computer controlled telephone apparatus comprised of a processor controlled telephone set, apparatus for interfacing the telephone set to a telephone network, a computer for interfacing the telephone set, comprising a stored telephony service program for receiving call control signals from the apparatus for interfacing the telephone set to the telephone network, and for controlling operation of functions of the telephone set in accordance with the stored telephony service program; and monitoring apparatus in the telephone set for monitoring operation of the telephony service program and in the event there is no operation of the controlling program, for causing direct connection of the telephone set to the apparatus for interfacing the telephone set to the telephone network.

Abstract: A method and device for decoding a sequence of signals in which information is derived, in part, from a duration of (a) one of the signals and/or (b) an inter-signal pause between two of the signals. The method and device may also be used to decode a signal to form decoded information, derived, in part, from a duration of the signal.

Abstract: A method and apparatus for detecting a stutter dial tone SDT signal. The method includes the steps of, receiving a received signal from a subscriber loop, generating a signal envelope of the received signal, generating a threshold parameter value from the signal envelope, counting the number of threshold parameter crossings undertaken by the signal envelope and producing a signal indicating SDT signal has been received when number of threshold crossings exceeds a predefined value.

Abstract: A signal detector includes a transform unit and a signal alignment unit. The transform unit is adapted to receive a plurality of frames of time domain input samples and generate a plurality of energy values based on the frames of time domain input samples. Each energy value is associated with one of the plurality of frames. The signal alignment unit is adapted to identify at least a first partial energy frame and a second partial energy frame from the plurality of frames. The first partial energy frame is associated with a first frequency and has a first energy value. The second partial energy frame is associated with a second frequency and has a second energy value. The signal alignment unit determines a misalignment between the first and second partial energy frames based on the first and second energy values. A method for detecting a signal is provided. The method includes generating a plurality of energy values based on the frames of time domain input samples.

Abstract: The present invention proposes a method and a device for detecting, amongst a set of signals, the presence of a periodic signal of period of occurrence T, in which a signal discriminating the said signal in the said set of signals is delivered. According to the invention, the discrimination signal is sampled in ln samples over more than one period T, a state value B(i) representing its level, and a true correlation value SR is calculated, by cumulating, for pairs of samples i and i+Z, the instantaneous value of correlation between the state value B(i) and the state value B(i+Z), the samples i and i+Z being located at instants shifted by a period T.

Abstract: A tone detector for detecting a multi-tone input signal in the presence of speech and noise, comprising first signal processors that generate output signals indicating the energy level of the input signal with the frequency of one of the component tones being amplified and the frequencies of all other of the component tones being attenuated, a last signal processor that generates an output signal indicating the energy level multiplied by negative one of the input signal with the frequencies of all component tones being attenuated, summing junctions that generate output signals indicating the energy levels of the sum of one of the first signal processor output signals and the last signal processor output signal, and tone validation logic receiving the summing junction output signals that generates a tone detect signal when the summing junction output signals indicate that the component tones satisfy a signaling standard.

Abstract: The present invention features a self-contained, programmable, telephone-activated emergency visual alert system. Low energy consumption LED visual alert "strobe" signal is directly powered from the inventive control unit. Multiple emergency telephone numbers may be programmed into the control unit making the inventive system highly effective for use in areas without standard "911" emergency dispatch service. In an alternate embodiment, the visual indicator may be located some distance away from the controller unit and be activated by means of an rf or other wireless control link. A small, inexpensive battery at the remote indicator may power the receiver and indicating lamp for long periods of time without the need for battery replacement. Programmable integrated circuits form the basis of the control circuitry allowing low component count, low power consumption and, ultimately, low cost and long term, reliable operation.

Abstract: AMPS (Advanced Mobile Phone System) ST (signalling tone) is detected by a tone detector in which samples of a demodulated signal are amplitude limited to remove click energy, and the limited signal is bandpass filtered, using a notch filter and summer, to limit it to the range of possible ST frequency. Power of the bandpass filtered signal is detected, and compared with detected power of a version of the bandpass filtered signal from which any sinusoidal signal has been eliminated, independent of frequency, to provide for ST detection. A function [x(k)+x(k-2)]x(k-2)-[x(k-1)+x(k-3)]x(k-3) for successive samples x(k) of the bandpass filtered signal is used for the sinusoidal signal elimination. The invention can also be used to detect other tones.

Abstract: To detect a dual tone pair signal in a telephone communication system, the signal is sampled at the Nyquist frequency. The sampled signal is filtered to determine the top three tone frequency power results. The input signal is then resampled at one-half of the Nyquist frequency. The resampled signal is filtered to determine signal power in the row and column frequency bands. The top three power results from tone filtering and aliasing row and column band pass filter power results are checked for lack of excess power to reject false digits.

Abstract: In a transmission system a pair of signalling tone signals is transmitted by a transmitter (2) to a receiver (6) via a transmission channel (4). In the terminal (6) a tone detector is used to detect the presence of the pair of signalling tone signals. In order to improve the reliability of the tone detector in the case of differing strength of both tone signals, the decision on the presence of the pair of signalling tone signals is based on a combined strength measure which is determined by an adder (23). The combined strength measure is compared with a reference level TH.sub.2. In a further embodiment, also a check on the level of the individual tone signals is done with comparators (11) and (9), in order to specify the maximum strength difference tolerated.

Abstract: Apparatus, and an associated method, for converting an inband signal, such as a DTMF signal, into a form to permit transmission thereof to a receive station. An inband signal, such as a DTMF signal generated by a wireline device is applied to a digital transmitter, such as a fixed cellular terminal having a digital transceiver. The inband signal is detected and encoded. The inband signal is encoded in a manner to permit its transmission according to an appropriate air interface standard.

Abstract: A system for, and method of, detecting a customer premises equipment ("CPE") alerting signal ("CAS") on a telephone line that is carrying near-end audio traffic and CPE embodying the same. The system includes: (1) an echo cancellation circuit, coupled to the telephone line, that detects an outbound component of the near-end audio traffic and produces, in response thereto, an echo canceling signal, (2) a combinatorial circuit, coupled to the telephone line and the echo cancellation circuit, that applies the echo canceling signal to an inbound component of the near-end audio traffic to produce a resulting signal having the near-end audio traffic substantially removed therefrom and (3) a CAS detector, coupled to the combinatorial circuit, that detects the CAS in the resulting signal, the echo cancellation circuit and the combinatorial circuit cooperating to increase the reliability of the CAS detector.

Abstract: An apparatus and method is disclosed for performing policing functions for specialized telephone services, and for mitigating fraudulent usage of such services in ubiquitous telephone networks that carry voice, facsimile or voice-band-data traffic. Signal processing is used to determine the properties of traffic present on a channel at a given point in time, and actions are conditionally imposed based on such traffic properties. A first embodiment of the invention can be applied to prevent fraudulent use of telephone services through suppression of an answer supervision response. A second embodiment of the invention can also be applied for regulation of access to specialized telephone services which depend on the manner of customers' use of such services.

Abstract: A user-authentication system includes an authorized user device (AUD) for transmission of DTMF tones to a user-verification system (UVS) over a telephone network, where user-verification is performed and authorized users are granted access to a desired service. In a memory module of the AUD, a plurality of passphrases and identifying data are stored for subsequent transmission to the UVS. The UVS includes a memory module for receiving and storing the passphrases and identifying data, and a processor for determining whether user-stated passphrases correspond to the stored passphrases, and for prompting the user with knowledge-based questions and determining whether the identifying data corresponds to answers given by a user in response to the knowledge-based questions.

Abstract: A dual tone multi-frequency detector includes a pulse code modulation expanding unit for converting pulse code modulation data into linear data. A correlating unit constructed from a plurality of correlators correlates the linear data with a plurality of predetermined reference signals to generate a plurality of power values of a frequency band corresponding to dual tone multi-frequency signals. A total power detecting unit detects a total power value of the linear data. A low frequency maximum power detecting unit detects a maximum low frequency power value from the power values of a low frequency band generated by the correlating unit. A high frequency maximum power detecting unit detects a maximum high frequency power value from the power values of a high frequency band generated by the correlating unit.

Abstract: A method and apparatus to avoid wrong detection when detecting signals including CAS (Call Alert Signal) formed by specific frequencies in the audio range, wherein frequency components forming a specific signal are detected from an input signal, and it is judged whether any signal component other than that of specified frequency range is included or not in entered audio range signal by comparing the energy level of the entered audio range signal with the energy level of only the specified frequency components extracted from the input signal. If any signal component other than that of the specified frequency range is judged to be included as a result of the energy level comparison, the signal is judged not to be the CAS signal.

Abstract: A method and system for transmission of control information over a separate channel to devices connected to a telecommunications network. An outdial node couples a destination system to a user who is accessing the destination system using a first communications pathway through a telecommunications network. When the destination system requests control data be entered, the user causes a signal to be transmitted on a second communications pathway. The signal, which includes information identifying the user and the desired control function, is transmitted by the user from a two-way pager. The signal is received by a paging system and transmitted to the outdial node. The outdial node accesses a database using the user identifying information and selects an entry corresponding the user and to the control function. The control data contained in the selected entry is then output to the destination system.

Abstract: A parallel-connected dialing signal detection and transmission-inhibiting device is disclosed which detects dual-tone multi-frequency dialing signals across tip and ring conductors of a telephone link and switches in an a.c. load that attenuates the dialing signals by at least 30 dB. This prevents action in response to the DTMF signals by a central office servicing the telephone link, thereby allowing commands-data to be transmitted within the home telephone wiring. Such commands can be used to invoke a speed/auto dialing function, to provide an intercom, to control appliances, etc. To allow fast response, the controller charges a capacitor of the a.c. load by connecting it across the tip and ring conductors in response to an off-hook condition. Then it is disconnected to allow a dial tone to reach a user at the telephone. Further transparency is provided by the fact that a single interfacing capacitor connects both the dialing signal detector and a tone generator to the tip line.

Abstract: A transmit control system using in-band tones for activating and deactivating one or more remote sites. The transmit control system detecting energy in two or more spectral regions to determine if the signal received is a harmonic signal or a signalling tone to prevent accidental deactivation of the transmitter system. In one application, a modified Goertzel algorithm is employed by a digital signal processor to provide tone detection and a two stage detection provides controlled switching in noisy environments.

Abstract: A three-way call detection and response system comprising, in accordance with a preferred embodiment, a three-way call detector coupled non-intrusively, by a bridge repeater, to a communication path carrying digital signals between originator and recipient end office telecommunication switches. The three-way call detector includes an interface and a digital signal processor electrically connected to the bridge repeater for receipt of digital signals from the communication path. The three-way call detector also includes a local controller which interacts with the interface, a digital signal processor, and a remote controller. The remote controller executes a plurality of software programs which control operation of the system. In accordance with a preferred method, the three-way call detection and response system monitors the communication path for indicia representative of a three-way call signature and, hence, an attempted three-way call placement.

Abstract: A telephone operated electrical switch for selectively energizing an electrical load in response to dialing of a predetermined telephone number. The electrical load may be the exterior light fixture of a dwelling, and the switch assembly may be configured to automatically flash the light on and off in response to the occupant dialing "9-1-1", so as to assist emergency response personnel in locating the dwelling.

Abstract: A communications detector for detecting remote user hang-up or disconnection by a telephone answering machine (TAM). The remote hang-up detector (RHUD) may operate in conjunction with a modem and does not affect transmission and receipt of modem signals and modem performance. An optically isolated voltage detector indicates to the TAM that the remote user has hung up by detecting reversal or interruption of the loop current supplied by the central office, thereby causing the local user or modem to likewise hang up.

Abstract: A method and device for detecting a customer premises equipment alerting signal (CAS) tone in a telephone system which has both caller identification and call waiting. The present invention distinguishes between valid CAS tones transmitted by the telephone company central office and invalid CAS tones which are caused by music or a human voice. The present invention samples detected tone during a plurality of sample periods. The change of frequency, as well as the direction of frequency change, between successive sample periods is calculated. The number of transitions in the direction of frequency change are counted and used to determine whether the detected tone corresponds to a valid CAS tone or an invalid CAS tone.

Abstract: A signal detection circuit includes band pass filters for detecting frequency components of a Call Alert signal (CAS) signal, a tone detection circuit for detecting whether or not a signal component is present in the output signals of the band pass filters, and two types of guard time setting circuits that have different guard times. When the CAS signal component is present, a transmitting speech signal is muted. Thereafter, with the guard time setting circuit having the normal guard time, it is determined whether or not the signal component lasts for a predetermined time period. Since the CAS signal is detected with two types of guard times, even if the transmitting speech signal contains a frequency component of the CAS signal, the transmitting speech signal is not mis-detected as the CAS signal.

Abstract: In a transmission system, a signalling tone is transmitted by a transmitter to a receiver via a transmission channel. In the receiver, a tone detector detects the presence of a signalling tone. In order to improve a reliability of the tone detector, a number of correlating elements which determine a correlation value between an input signal and a reference signal are used. Absolute output signals of the correlating elements are added by an adder to derive a combined correlation signal to be used for detection.

Abstract: In a transmission system, a tone is transmitted by a transmitter to a receiver via a transmission channel. In the receiver, a tone detector is used to detect the presence of a signalling tone. In order to improve a reliability of the tone detector when the arrival of the signalling tone is unknown, a number of correlators having mutually displaced measuring periods are used. More than two correlators are used in order to reduce the measuring period, also resulting in an improved reliability of the tone detection.

Abstract: The total energy of a signal that has entered from a telephone line is detected before the signal is applied to an AGC circuit. After the signal is applied to the AGC circuit, the energy of a DTMF signal, which comprises one frequency from four high group frequencies and one frequency from four low group frequencies, is detected through a band-elimination filter having a short energy-propagation delay time with respect to pass-band frequencies. By detecting the DTMF signal based upon the detected energies, detection of the DTMF signal can be performed in a short period of time and erroneous detection can be suppressed.

Abstract: A method and apparatus for determining when an echo canceller should be disabled in a telephoning system is disclosed. First, a first power estimate is determined from an input signal. In addition, the input signal is divided into in-phase and quadrature components. The in-phase and quadrature components are then subsampled and used to determine a second power estimate. The first and second power estimates are compared to determine whether a predetermined tone is present. When the predetermined tone is detected, the present invention determines whether a phase reversal in the predetermined tone is present by using the in-phase and quadrature components. When the phase reversal is detected, the echo cancellers are disabled.

Abstract: An improved dual tone multifrequency (DTMF) or multitone signal detector which more efficiently detects DTMF signals. For each received frame, the present invention initially performs only a portion of the Goertzel DFT algorithm for each of the possible tone frequencies and then analyzes the interim accumulated energies. The DTMF detector then selects one or more frequencies from each of the tone groups which have the largest energy values, and the detector only completes calculation of the Goertzel DFT algorithm on those selected one or more frequencies. In other words, the DTMF detector discontinues calculation of the Goertzel DFT algorithm on one or more frequencies which have low accumulated interim energies. This reduces the computational requirements and provides improved performance.

Abstract: A system and method for analyzing audio signals sampled from a telephone line during moving sample windows in order to detect indicia of three way calling attempts. The system and method sample audio signals on the telephone line, sort the sampled signals into a profile of levels for the sampled audio signals, and monitor the profile of sampled audio signals for reset and reference conditions. Reset conditions are pulse patterns identified from sampled audio signals that are inconsistent with patterns generated by three way call events. Reference conditions are pulse patterns identified from sampled audio signals that are consistent with patterns generated by three way call events. A sampling window and its associated profile are reset when reset conditions are detected. The profile is tagged as a potential three way call event when reference conditions are detected in a sample profile and no reset conditions are detected over the selected sampling interval (sampling window).

Abstract: Digital data is encoded into a series of analog waveforms, called symbol waveforms, created as the result of interference of sinusoidal wave interference patterns. Each of these symbol waveforms is an encoded version of N-bits of data. These encoded symbol waveforms is an encoded version which are very different, in both appearance and in propagation properties, from traditional voltage state signaling or pulse codes. The encoded symbol waveforms are formed by generating and superimposing a set of analog sinusoidal waves, where the gain and phase shift of each wave is computed so as to provide, in combination, a unique interference pattern that can be recognized, via signal processing techniques, by a detector and then decoded. The symbol waveforms are computed so that successive symbol waveforms seam together to form a smooth continuous AC analog signal that does not itself generate interference frequencies, can be bandpass filtered, and is suitable for long distance propagation.

Abstract: An information signal detection device and an information signal detection method are disclosed with which it is possible to transmit information by means of a DTMF signal using a channel that is prone to distortion, such as a high-efficiency channel. The information signal detection device comprises a filter bank component and a logic component. The filter bank component receives via a channel an information signal in which are superposed sine waves of two different frequencies selected from a specific number of frequencies sent by the sender, and generates binary information patterns showing in binary information whether the signal components of the various frequencies of this information signal are present. The logic component recognizes the end of the signal region when the binary information pattern generated in the binary information pattern generation step is containing no binary information showing that a signal component is present continuously for a specific period of time.

Abstract: A service node provides a shared added value service within a telephony network, such as a public switch telephone network. Peripheral devices, such as speech applications platforms shared announcement platforms and message recording platforms, are connected to a switch which operates under the control of a central control computer. The switch includes distributed processors responsive to externally originating signals, such as DTMF signals, generated while calls are being processed. The distributed processing devices supply information derived form said signals to the central control computer. Thus, it is no longer necessary for a central control computer to examine ongoing calls in order to detect the presence of DTMF signalling. Detection of DTMF signalling is performed locally and information is returned back to the control computer only when relevant information has been detected.

Abstract: A device capable of analyzing call progress event information from sensors connected to switched network circuits for the purpose of identifying the beginning and end of a telephone call. The invention also collects and analyzes all events occurring between the origination and termination of the call, providing a detailed description of both telephone user and network element actions. Abnormal events are identified during this analysis so that call quality can be determined. The invention can use information supplied by sensors that are intrusive or non intrusive to the switched network circuit.