Abstract: A device for detecting a transmission of at least one of a first communication signal and a second communication signal in a communication network is disclosed. The first communication signal is transmitted within a first frequency band, and the second communication signal is transmitted within a second frequency band. The device includes a housing and a filter circuit in the housing. The filter circuit is adapted to communicatively interface with the communication network and includes a first circuit path for passing the first communication signal, wherein the first circuit path includes a first indicator for providing a first indication of the passed first communication signal. The filter circuit further includes a second circuit path for passing the second communication signal, wherein the second circuit path includes a second indicator for providing a second indication of the passed second communication signal.

Abstract: A VDSL customer drop testing arrangement and equipment utilizes a test set top box having a sign-on identifier unique to an authorized test device to perform testing of the customer drop without the need to provision the drop for receipt of video programming or data services from any network information or service providers (VIPs or DSPs). Because the test arrangement of the present invention does not require such provisioning, isolation of the customer drop is achieved. Such isolation insures that the test set is not being affected by problems originated from a VIP or DSP.

Abstract: A system and method are presented for providing a telephone service. An analog signal is received from a telephone and the analog signal is converted into a digital signal in a first format. A modem is provided for receiving the digital signal in the first format. A digitizer is also provided for receiving the analog signal from the telephone. The system, in a first mode of operation, couples the digital signal in the first format to the modem, and in a second mode of operation, couples the analog signal from the telephone to the digitizer. The second mode of operation may be, for example, a power failure mode of operation.

Abstract: In the course of a reflectometry-based qualification procedure of a local loop, which connects customer premises to a central office of a telecommunication network, and in the event of being unable to identify the loop termination associated with the customer premises, a second reflectometry measurement of the local loop is carried out with a different impedance load at the customer premises. Next, the two reflectograms are compared with each other in the time domain in order to delineate among all the reflections those at the customer premises and to determine therefrom the position of the customer premises in the local loop.

Abstract: Methods and systems for proactively maintaining Digital Loop Carriers and a telephone system local loop. One embodiment for proactively maintaining a Digital Loop Carrier in a telephone system local loop includes communicating with a communications network and acquiring status information associated with the Digital Loop Carrier. Proactive maintenance is predicted based upon the status information. The status information may be weighted. The status information may also be combined with information from a Dynamic Network Analyzer and information from a Loop Facilities and Control System. The embodiment may also generate and dispatch work order information describing the predicted proactive maintenance. A further embodiment includes communicating with a communications network and acquiring at least one of customer information associated with copper line pairs, service information associated with copper line pairs, and status information associated with a Digital Loop Carrier.

Abstract: A method and system for qualifying telephone lines for high speed data services. The system takes measurements on a line under test and matches those measurements to a model of a line. The model of the line is used to predict whether the line will support data services at a particular level. If the model of the line includes a service affecting condition that is removable from the line, a new model is created reflecting the line as it would appear with the service affecting condition removed. The new model is then used to predict performance. If the required performance level is predicted based on the new model, the line is categorized as a line that can not support the required level of data services, but could if repaired. In this way, an accurate and useful prediction of line performance is provided.

Abstract: An apparatus for and method of remotely controlling electronic devices, such as telecommunication equipment attached to telephone lines, test equipment, and/or home electronics includes a master board (105) having its own IP address and arranged and constructed to receive (401) instructions via the internet (103) from a remote terminal (101). The instructions are interpreted and converted into one or more commands that are directed (405) to a slave board (113 or 117) that performs, in response to the command(s), one or more operations on a telephone line and its associated hardware and/or software (115), a piece of test equipment (125), lights (123), or other type of electronic device. Any results of the operations may be returned to the terminal (101).

Abstract: A central office modem (50) that includes the capability of single-ended loop testing (SELT) is disclosed. The modem (50) includes a digital signal processor (54), a codec (56), line driver and receiver circuitry (58), and a hybrid circuit (60), by way of which a subscriber loop (LOOP) can be driven and sensed. The line driver and receiver circuitry (58) may include a transformer (74a, 74b) for driving the loop (LOOP), or the output may be capacitively coupled. The line driver and receiver circuitry (58) includes active termination, by way of operational amplifiers (80a, 80b). Switches (82a, 82b; 84a, 84b) are provided to selectively enable and disable the active termination function, and to selectively bypass or include the hybrid circuit (60). This control of the line driver and receiver circuitry (58) provides the ability to calibrate out its own characteristics, providing high precision SELT measurements of the load impedance type, and of frequency domain reflectometry, and time domain reflectometry.

Abstract: A method and apparatus for internally testing portions of a subscriber loop interface circuit. Testing may be conducted on a semiconductor circuit including the subscriber loop interface circuit. The portion of the subscriber loop interface circuit being tested may be the ring trip detector and/or the off-hook detect circuit. Testing may be conducted without disabling the capability of the subscriber loop interface circuit to monitor the hook status of a subscriber.

Abstract: An apparatus and technique for determining whether a telephone loop is capable of carrying a Digital Subscriber Line (DSL) signal. Time domain reflected (TDR) signals that are echoes of transmit impulse signals are processed using time domain echo averaging and echo enhancement using second-order statistics. Each technique allows clearer visualization of the TDR echo signal by reducing the noise and distortion present in the TDR signals. These statistical signal processing techniques allow determination of telephone loop characteristics such as loop length once the TDR echo signal amplitude and time index are calculated.

Abstract: Interfacing to and controlling POTS line conditioning devices using a Voice Interface Unit (VIU) are described. Technicians perform tests and checks while a POTS line is in a conditioned state. The VIU provides a centralized voice input/voice output interface allowing technicians to identify and request various conditioning options using speech. The VIU identifies a line conditioning unit to be used to test a line corresponding to a phone number via a database lookup. The VIU controls the identified line conditioning unit to connect to the POTS line. The VIU provides the technician with an easy to use voice input/output universal interface irrespective of the particular manufacturer/model of line conditioning device by performing conversions to the various protocols and instruction sets used by different manufactures. The VIU includes individual security controls and multiple access levels. The VIU may include load/simulator, call back, and keypad test capability.

Abstract: The present invention relates to a frame communication system composed of a code converter and a frame generator/decomposer. In order to improve a line efficiency without encapsulating transmitting data, a code converter in a frame transmitting device converts at least different specific codes X and Y within the transmitting data respectively into codes (Y, A) and (Y, B) composed of the code Y and at least specific codes A and B different from each other, and a frame generator prepares a frame of the transmitting data with the code X as a frame boundary. A frame decomposer in a frame receiving device recognizes a specific code X as a frame boundary to decompose receiving data, and a code converter converts codes (Y, A) and (Y, B) within the receiving data composed of a specific code Y, and specific codes A and B into codes X and Y.

Abstract: A method and apparatus for qualifying a telephone transmission line for XDSL communication services is disclosed. The system includes a modem, located at the customer premises to be connected. The modem analyzes actual signals to determine the electrical characteristics of the communication channel associated with the customer premises. The modem includes a transmitter, receiver and controller to generate test signals and receive responses. The modem then analyzes the data to generate an output value indicative of the electrical characteristics of the communication channel being tested. This output value is then displayed to a user or transmitted over the communication channel to a network. The system thereby eliminates the necessity of dispatching a technician to test the telephone line, and provides more accurate test results than those achievable at the network-side of the connection alone.

Abstract: Systems and methods for remotely diagnosing, trouble shooting, and/or programming an end user telephone by a customer service representative using a telephone and modem system in communication with the user's telephone and modem system during a live telephone call between the customer service representative and the user are disclosed. The method for the user to obtain assistance from the customer service representative for the user system generally comprises initiating a telephone call to the representative, transmitting data signals containing information relating to the user system to the customer service system, speaking with the customer service representative, and receiving data signals that includes a command to control a remotely controllable feature of the user system from the customer service system, wherein the user and customer representative systems selectively alternate between data signal transmissions and voice signal transmissions.

Abstract: A system and method for maintaining network activity in a router to keep the router from entering a lock-up state due to inactivity. The system and method is operable to send a ping request via the router to an Internet Protocol (IP) address to which a response is expected. It is then determined whether the response is received. If no response is received, a notification message is displayed indicating that network access is unavailable. The process is preferably automatically repeated such that the network router does not experience a prolonged period of inactivity and the user is apprised of the status of his network connection.

Abstract: A method and system are provided for generating a graphical representation of call-specific data in a wireless network in conjunction with Xtel and Lucent equipment. The method includes performing a first phone call using the Xtel equipment to obtain a first set of call-specific drive test data from an area covered by the wireless network. This first set of data includes at least a time associated with the first phone call. The method also includes performing a second phone call using the Lucent equipment to perform an RF call trace. This second phone call is made in connection with the drive test and provides a second set of call-specific data. As for the first set of data, the second set of data includes at least a time associated with the second phone call. Next, the method includes combining the first and second sets of data into a combined output file based on common time information.

Abstract: The invention is a method and system conducting a completion test on a communications line. The system includes a testing device coupled to a remote device by a network. Line-test results are received from the testing device and made available to various client devices via the same or another network. Test data is automatically archived for analysis.

Abstract: In one embodiment, a new device or service can be treated as an abstraction, allowing a model to be created which mimics operation of the device or service, but which does not physically exist. A communication system may then take physical assets that are distributed around a network, such as circuit packs with ports on them, and virtually plug them into a shelf that does not physically exist. A legacy system preferably continues to function as it always has and the abstraction mediates between the legacy operations support systems, the virtual machine and the physical reality. This then allows for the continued use of existing operation systems to manage new network architectures with services different from those originally contemplated by the legacy operations support systems.

Abstract: An apparatus and method are provided for obtaining, from an analog subscriber loop, test data that may be used to test the performance of a telephony communication system. The apparatus includes a digital-to-analog (D/A) converter, a first port, a second port, and an analog-to-digital (A/D) converter. The D/A converter receives digital data and converts the digital data into a first analog signal. The first port transmits the first analog signal across a first subscriber loop to a telephony communication network. The network, via A/D and D/A conversion, translates the first analog signal to a second analog signal and transmits the second analog signal to the second port via a second subscriber loop. The A/D converter receives the second analog signal from the second port and converts the second analog signal into the digital test data, which is then used to analyze the performance of the telephony communication system.

Abstract: The present invention provides a method and apparatus for performing line qualification tests, and binning the results of such testing. The lines are tested to determine or estimate various characteristics of the line. Physical characteristics of the line may be estimated (e.g. line length, line gauge, insertion loss). The presence of devices on the line such as load coils, bridged taps, terminations and the like may also be determined. A prediction of the data rate the loop can support is made from the measured and estimated line conditions. The results are binned according to certain criteria and to provide an easily discernable status of the line. The binning can be performed by a computer using software designed specifically for this purpose. The binned results may include a first category indicating the line cannot support a certain level of high speed access. The binned results may also include a second category indicating the line can support a certain level of high speed access.

Abstract: Methods and apparatuses are disclosed for locating trouble in a telecommunications network. One method communicates signals from a central office along a local loop. The local loop comprises a ring wire and a tip wire. Voltage polarity between the ring wire and the tip wire is reversed, causing a customer's wiring to be isolated from the local loop. A test of the local loop may then be remotely performed to determine whether trouble exists in the local loop.

Abstract: A method and system are provided for generating a graphical representation of call-specific data in a wireless network in conjunction with Xtel and Ericsson equipment. The method includes performing a first phone call using the Xtel equipment to obtain a first set of call-specific drive test data from an area covered by the wireless network. This first set of data includes at least a time associated with the first phone call. The method also includes performing a second phone call using the Lucent equipment to perform an RF call trace. This second phone call is made in connection with the drive test and provides a second set of call-specific data. As for the first set of data, the second set of data includes at least a time associated with the second phone call. Next, the method includes combining the first and second sets of data into a combined output file based on common time information.

Abstract: The present invention is directed to an acoustic signal transfer device for transferring an acoustic signal produced by a telephone handset in a test setup. The device comprises a handset holder, a microphone holder and an acoustic pathway that extends from the handset holder to the microphone holder. The handset holder supports a telephone handset and allows an acoustic signal to travel from the telephone handset to one end of the acoustic pathway. The microphone holder supports a microphone and allows an acoustic signal to travel from a second end of the acoustic pathway to the microphone. A system and method for utilizing the acoustic signal transfer device in a radio frequency immunity test for a telephone are also disclosed.

Abstract: An apparatus and a method for determining faults in a telephone line. The apparatus has an enclosure housing a switch. The switch is for electrically communicating with a ring wire of a telephone line, with a tip wire of the telephone line, and with an electrical ground. The switch selectively permits electrical communication between any two of the ring wire, the tip wire, and the ground. The apparatus improves testing of the telephone line by helping identify an electrically open condition in the telephone line.

Abstract: A system for identifying a handset used over a communication network comprises a composite database including training data for a plurality of handset types, a plurality of support vector machines trained to identify, respectively, at least one of the plurality of handset types, and an interface operable to receive audio testing data for an unidentified handset. Each support vector machine is configured to determine its degree of recognition of the audio testing data. The system also includes a processor configured to identify unidentified handset by determining the support vector machine exhibiting the highest degree of recognition.

Abstract: A method of allocating subscriber lines in a telecommunications network into speed bins. With the method, more intelligent business actions can then be taken in the provision of high-speed data services over the subscriber lines. For example, only qualified lines might be used for high-speed data services, with the other lines being allocated to POTS service. The lines are divided into speed bins using a pair of neural networks, with one predicting upstream speed and one predicting downstream speed. The combined predictions are then mapped to a speed bin, which is the basis for further business actions. The disclosure describes that the neural networks are created using conditional fuzzy logic to precondition the neural networks by line speed.

Abstract: A method of monitoring real-time communication on a computer network between at least two client computers connected by the network comprising first providing a database of keywords, with each of the keywords linked to a predefined rating. The method then includes monitoring real-time communication on a computer network between at least two client computers connected by the network; detecting the keywords in the real-time communication; and determining for the real-time communication a rating level based upon the predefined rating of the keywords. The keyword may consist of text, audio, video and graphical communication, for example. Preferably, the rating level of the real-time communication is conveyed to at least one of the client computers. More preferably, at least one additional client computer receives the real-time communication, and the rating level of the real-time communication is conveyed to the at least one additional client computer.

Abstract: A method characterizes a customer line for data transmission. The method includes measuring electrical properties of the customer line from a central location, identifying a line model from the measurements, and identifying a modem model for a modem selected for use with the customer line. The modem model gives performance data for the selected modem. The method also predicts performance data for the customer line when operated with the selected modem by combining the line and modem models.

Abstract: A method and system are provided for generating a graphical representation of call-specific data in a wireless network in conjunction with Comarco and Hughes equipment. The method includes performing a first phone call using the Xtel equipment to obtain a first set of call-specific drive test data from an area covered by the wireless network. This first set of data includes at least a time associated with the first phone call. The method also includes performing a second phone call using the Lucent equipment to perform an RF call trace. This second phone call is made in connection with the drive test and provides a second set of call-specific data. As for the first set of data, the second set of data includes at least a time associated with the second phone call. Next, the method includes combining the first and second sets of data into a combined output file based on common time information.

Abstract: Allowing a tester of a telephonic device to issue call control commands to a call control server using an intuitive set of commands and using both data lines for data call control commands, and voice lines for touch tone or “DTMF” call control commands. The user may initiate a call control command by either entering the call control command in a command line of a program executed at a telephonic device, or by crafting a function call using an Application Program Interface (API) that allows for more intuitive function calls that are more descriptive of the call control command. During execution, the more descriptive user-entered command or function call is converted into a form that recognized by the call control server. The converted call control command is then transmitted to the call control server.

Abstract: A method for testing subscriber loop conditions includes receiving test signal data from a test signal provider, receiving a request for transmitting a test signal described by the test signal data, and transmitting the test signal over a subscriber loop. The test signal may correspond to a pre-qualification test signal, a qualification test signal, or an in-service test signal. Test results may be transmitted to the test signal provider or to some other designated.

Abstract: A method for the direct estimation of configuration parameters defining the make-up of a physical system, such as cable lengths and gauges in the case of telephone subscriber loops, from boundary or end-point measurements of the physical structure, such as the impedance or return loss response of a subscriber loop, due to a probing source.

Abstract: A Digital Subscriber Line Access Multiplexer includes a set of line cards, a set of xDSL modem cards, a redundant xDSL modem card, a test and switching unit, a control unit, and a trunk unit. Each line card may include a switch, through which the control unit may selectively direct the line card to couple to a corresponding xDSL modem card or a redundancy bus. The test and switching unit is coupled to the redundancy bus, and includes a relay matrix and a Copper Loop Tester (CLT). In response to commands received from the control unit, the relay matrix may route redundancy bus signals to the CLT and/or the redundant xDSL modem card. The CLT performs tests to measure or determine subscriber loop electrical characteristics in response to control unit commands, and returns test results to the control unit.

Abstract: A characteristic of a local loop is used to estimate the loop's data carrying capacity. The characteristic is measured and applied to a table previously stored in memory which contains values relating the characteristic to downstream data rates. Using interpolation when required, an estimate of the data carrying capacity of the local loop is estimated based on the measured characteristic. The measured characteristic may be, for example, the input impedance or the DC resistance of the local loop.

Abstract: A digital subscriber line access multiplexer overlay onto a digital loop carrier system for transporting high speed digital data over an existing backplane which carries voice, data, and test signals between voice line cards and a carrier line. The voice signals are time division multiplexed into frames. The system includes a data bus interface for impressing the high speed data on a subset of existing backplane buses for transport along the backplane and for retrieving high speed digital data from the backplane buses. The system further includes a plurality of data line cards for connecting to the backplane and backplane subset conductors, the data line cards being adapted to couple the high speed data between the subscriber line and the backplane, whereby the high speed digital data can be routed over the backplane subset to any of the digital data line cards without interfering with the voice signals routed to voice line cards.

Abstract: Customer services terminal input connected between telephone exchange and outputs. Interface circuits provide service between input and outputs Test means applies test conditions to interface circuits and/or to outputs associated with the interface circuits, and/or to ring/tip pairs associated with interface circuits, and/or to telephone lines associated with interface circuits Other interface circuits service input to other outputs Test means analog-to-digital converter includes reference input, analog measuring input, ground potential input, and test output Normally de-energized calibration relay has normally-closed switches and normally-open switches. Normally-closed switch connects reference voltage to reference input. Another normally-closed switch connects analog measuring input to test means generated voltage.

Abstract: Methods and systems for proactively maintaining a telephone system local loop. One embodiment includes acquiring at least one type of information selected from the group consisting of information from a Dynamic Network Analyzer and information from a Loop Facilities and Control System. This information is stored in memory, and the stored information is combined. This method may also include predicting proactive maintenance based upon the combined information. Another embodiment includes communicating with a communications network and acquiring at least one type of information selected from the group consisting of customer information associated with copper line pairs and service information associated with copper line pairs. The acquired information is stored in memory and combined to predict proactive maintenance of the telephone system local loop. Still another embodiment describes a system including software modules communicating with a communications network.

Abstract: A telecommunications system includes a telephone exchange and a customer services terminal whose input is connected to the telephone exchange, and whose plural outputs are individually connected to one of a plurality of telephone lines. A plurality of interface circuits within the customer services terminal are individually connected intermediate the input and one of the plural outputs. Self-test means provides for the testing of selected interface circuits. Loop-test means provides for the testing of selected telephone lines. A self-test relay is responsive to the self-test means and operates to disconnect the selected outputs from corresponding telephone lines as self-test conditions are applied to selected interface circuits as these interface circuits are disconnected from the selected telephone lines. The loop test means applies loop-test conditions to selected interface circuits, while the selected interface circuits and the corresponding outputs remain connected to the corresponding telephone lines.

Abstract: A controllably switched arrangement selectively couples multiple circuit functions, such as reverse polarity detection, ring-trip and line voltage measurement, of a telecommunication card to the same external programming component (e.g., capacitor) on an as needed basis, by means of associated coupling circuits and a controlled switching circuit. The coupling circuits are controllably enabled/disabled in association with the particular circuit function required, while the controlled switching circuit selectively connects each coupling circuit with the external component. Through combined control of the coupling circuits and the switching circuit, respectively different circuit functions can be implemented with the same external component.

Abstract: A telecommunications system includes a customer services terminal that is connected intermediate a telephone exchange and a user location that has a plurality of telephone lines. The customer services terminal and/or the telephone lines are tested by providing a web server within the customer services terminal. The web server includes a graphic user interface that enables the selection of self-test to be applied to selected portions of the customer services terminal, and/or enables the selection of loop test to be applied to selected ones of the plurality of telephone lines. Selected self-tests are applied to selected portions of the customer services terminal, and/or selected loop-tests are applied to selected ones of the plurality of telephone lines, as a remainder of the customer services terminal and/or a remainder of the plurality of telephone lines remain operative to supply telecommunications services to the user-location.

Abstract: The invention includes a system and a method for testing a communication network. The inventive method transmits a first signal from a first point to a second point of the communication network, where the first and the second points are remotely located. The inventive method further includes recording a first time value of the transmitting of the first signal using a first clock, receiving a second signal at the second point of the communication network, and recording a second time value of the receiving using a second clock. The first clock and the second clock operate from a substantially similar reference. The method may further include comparing the first signal and the second signal as a function of the first and second time values. Also, the method may determine at least one performance characteristic of the communication network based on the comparison.

Abstract: A system and method of communicating between a central office and a plurality of subscriber sites. Subscriber sites are separated into frequency groups. Each group spans a distance along the cable such that no more than a predetermined amount of attenuation is required to equalize the signal power of signals sent from a site in the group. Frequency groups closer to the central office are assigned higher frequency bands than frequency groups farther away from the central office. The central office includes a plurality of filters, each of which has a passband for passing the frequency band of a group and a stop band that substantially attenuates the frequencies of the other groups. The frequency group nearest the central office has no filter. The passband of a filter may also provide any needed attenuation to assure that signals arriving at the central office have approximately the same power levels.

Abstract: A system and method for testing lines in a network. The system and method are described in connection with a system for use with a telephone network to aid a network operator determine whether the any line can support high speed data services. According to the method, a mapping is created between low frequency measurements and average loop loss over a high frequency range. The average loop loss is sued to compute the equivalent working length of a line, which is an industry standard measure of the ability of a line to support high speed data services.

Abstract: In a subscriber testing system, a V5 interface protocol is used as a communication protocol. A switch includes a processing unit for transmitting to a communication node a piece of test specifying information, inputted from a maintenance/operation terminal, for indicating a subscriber test for a subscriber's line and subscriber circuit that correspond to an accommodated subscriber by use of specifying information of a message type based on the V5 interface protocol. The communication node includes a processing unit for making a testing device execute the subscriber test on the basis of the test specifying information received via a logical link from the switch, and sending test result information for informing of a result of the test back to the switch by use of specifying information of a message type based on the V5 interface protocol.

Abstract: A method and system for measuring the signal transmission time through a network link bounded by at least one echo canceller. The method generally includes the steps of determining a signal transmission time (tA) along a network path including the network link bounded by the echo canceller between a first endpoint and a second endpoint, transmitting a test signal from the first endpoint to the second endpoint through the network path, transmitting an echo signal which simulates the test signal from the second endpoint to the first endpoint through the network path, measuring a minimum time delay between transmission of the test signal and transmission of the echo signal which causes the echo canceller to cancel the echo signal and calculating the signal transmission time through the network link bounded by the echo canceller based on the measured minimum time delay and the determined network path signal transmission time (tA).

Abstract: A technique for qualification of loops for new digital subscriber line services (DSL) involves use of an expert system, such as a neural network. A database of loop characteristic information and performance data enables the expert system to train or learn how to predict performance for future loops. In response to data characterizing a new loop to be qualified, the trained expert system predicts digital subscriber line performance for the new loop. Typically, the prediction enables classification of service capacity for the new loop into one of several classes corresponding to levels of DSL service offered through the network. The database for use by the expert system is updated as each newly qualified loop is brought into service and actual performance for that loop is known.

Abstract: A single ended, frequency domain reflectometry signal processing based scheme measures loop loss of a telecommunications wireline. A distortion-corrected, normalized data array is differentially combined with an associated set of wireline noise spectrum values. The resulting noise margin data is processed by a Shannon Theorem operator, to produce a set of N frequency bins, each containing the number of bits which the link will support for a respective tone. The bit contents of the bins represent a composite bit rate that is available for use for ADSL signalling.

Abstract: A line card or other telephone or communications interface provided with a ringing SLIC outputs relatively high voltage, such as in excess of about 90 volts, and/or relatively high current such as in excess of about 20 milliamps during normal use, but decreases the voltage or current of a ringing signal or other signal upon occurrence of a tip and/or ring line fault or other abnormal condition. The abnormal condition is detected by measuring voltage and/or current on the tip line and/or ring line. In response to an excess voltage or current, the ringing current or other output current is reduced to achieve desired safety and/or compliance with standards.

Abstract: Single Ended Line Probing (SELP) techniques for devices having transformerless hybrid circuits are disclosed. These SELP techniques provide an accurate estimate of the length of a transmission medium (e.g., subscriber loop in Digital Subscriber Line (DSL) system) by computing a transfer function that accounts for the characteristics of the transformerless hybrid circuit and the transmission medium, and relating the transfer function to the length of the transmission medium at one or more frequencies.

Abstract: A system for centrally and remotely testing switches of cellular and conventional telecommunications network wherein a controller located at a remote location provides instructions to Remote Call Processor (RCP) to thereby prompt the RCPs to establish a communication link from the RCP through a switch to a destination device whereby audio from said destination device is communicated, by way of the switch and the RCP, to the controller in order to verify that the switch properly routed and billed of the call. The destination device may be a service provided by such network or it may be another RCP.