testing a communication interface connected to an analog telephone line

Abstract

A method for testing a communication interface connected to an analog telephone line comprising two electrical wires, the method comprising the following steps: if it is detected that the communication interface goes into an off-hook state, collecting measurements acquired by the communication interface; if the measurements have nominal values, implementing processing. During the processing, if it is detected that the communication interface remains in the off-hook state for a predefined period, controlling (202) an additional test on the telephone line; if the test reveals a fault in the analog telephone network, transmitting (204) an alarm, and otherwise repeating the processing. Figure for the abstract: Fig. 4

Description

Title of the invention: testing of a communication interface connected to an analog telephone line FIELD OF THE INVENTION

[0001] The present disclosure relates in particular to a method for testing a communication interface connected to an analog telephone line. STATE OF THE ART

[0002] A component used as a communication interface between an analog telephone network and a digital network providing access, for example, to a voice over IP (Voice Over Internet Protocol) service is the FXS (Foreign exchange subscriber) port.

[0003] An FXS port can take both states: • an “off-hook” state when the FXS port considers itself to be connected via an analog telephone line to an off-hook telephone device (in other words, when the FXS port considers that the analog telephone line is busy), and • a so-called “on-hook” state where the FXS port considers that it is not connected to any off-hook telephone device (in other words, when the FXS port considers that the analog telephone line is not busy).

[0004] The FXS port may declare itself in the off-hook state for various reasons: due to a malfunction of the FXS port, due to a problem connecting the FXS port to the analog telephone network, or because the analog telephone line is genuinely busy, either by a call in progress or because a user has voluntarily picked up his telephone so as not to be disturbed.

[0005] To discriminate between these different cases, it is known to order the FXS port to implement tests on the telephone line which are defined in the standard known to those skilled in the art under the name GR-909 (the name of the specification describing the content of this standard is “GR909-CORE: Generic Criteria for Fiber in the Loop Systems”).

[0006] However, these tests are not always accurate.

[0007] Other tests have been proposed in document US6438212B1, but these have the disadvantage of requiring external equipment as well as user intervention. Statement of the invention

[0008] An aim of the invention is to test a communication interface with a precise analog telephone network and not requiring external equipment.

[0009] To this end, according to a first aspect, a method is proposed for testing a communication interface connected to an analog telephone line comprising two electrical wires, the method comprising the following steps: • detection of a change in state of the communication interface between an off-hook state and an on-hook state; • if it is detected that the change of state goes from the on-hook state to the off-hook state, collection of measurements acquired by the communication interface, the measurements relating to at least one of the following physical quantities: • a voltage supplied by a converter of the communication interface, • a voltage between the two electrical wires, • an intensity of a loop current flowing in one of the two wires electric, • an intensity of a leakage current from one of the two electrical wires to a ground of the communication interface; verification of correspondence of measurements with respective nominal values; if the verification reveals that all measurements have nominal values, implementation of a treatment comprising the following steps: • detection of maintenance of the state of the communication interface for a predefined duration; • if it is detected that the communication interface remains in the off-hook state for the predefined duration, command of an additional test on the telephone line by the communication interface, so as to collect diagnostic data complementary to the measures; • if the additional diagnostic data reveals a fault in the analogue telephone network, an alarm is issued; • if the additional diagnostic data do not reveal a fault on the analog telephone line, repeating the processing.

[0010] The method may also include the following optional features, taken alone or combined with each other whenever technically possible.

[0011] Optionally, the method comprises the following steps: if the verification of the measurements reveals that at least one measurement among the voltage between the two electric wires, the intensity of the loop current and the intensity of the leakage current does not have a nominal value, control of the additional test on the telephone line by the communication interface, so as to obtain the diagnostic data complementary to the measurements, and alarm emission if the diagnostic data reveals a fault in the analog telephone network.

[0012] Optionally, the method comprises the following steps: • if verification of the measurements reveals that the supplied voltage does not have a nominal value, command to restart the communication interface converter; • if the verification of the supplied voltage has a nominal value, verification of correspondence with respective nominal values ​​of at least one measurement, the measurements relating to at least one of the following physical quantities: • the voltage between the two electrical wires, • the intensity of the loop current, • the intensity of the leakage current.

[0013] Optionally, the method comprises the following steps implemented if it is detected that the change of state goes from the off-hook state to the on-hook state or if the communication interface remains in the on-hook state, • collection of a voltage between the two electrical wires acquired by the communication interface; • verification of the collected voltage, so as to determine whether the collected voltage has a nominal value; • if the voltage has a nominal value, implementation of the treatment; • if the voltage does not have a nominal value, access to stored information by the communication interface, information indicating whether the communication interface has received a command to supply power to the analog telephone line or not; • if the information indicates that the communication interface has not received a power supply command, then command the communication interface so that the communication interface supplies power to the analog telephone line; • if the information indicates that the communication interface has received a power supply command, command to restart the converter.

[0014] Optionally, the method further comprises the following steps implemented after the command of the communication interface so that the communication interface supplies the analog telephone line: • collection of new measurements acquired by the communication interface, the new measurements relating to at least one of the physical quantities; • verification of correspondence of the new measurements with the respective nominal values; • if the correspondence check of the new measures reveals that all the new measures have nominal values, implementation of the treatment • the correspondence check of the new measurements reveals that at least one of the new measurements does not have a nominal value, command to restart the converter.

[0015] Optionally, the method further comprises the following steps implemented after the converter restart command: • repetition of the steps of collecting and verifying new measurements; • if repetition of the steps of collecting and verifying new measurements reveals that all the new measurements have nominal values, implementation of the treatment; • if the repetition reveals that a new measurement does not have a nominal value, hardware reset command of the communication interface.

[0016] Optionally, the method further comprises the following steps implemented after the hardware reset command of the communication interface: • second repetition of the steps of collecting and verifying new measurements; • if the second repetition reveals that all the new measurements have nominal values, implementation of the treatment; • if the second repetition reveals that a new measurement does not have a nominal value, an alarm is issued.

[0017] Optionally, the complementary test includes at least one test defined by the GR-909 standard.

[0018] A second aspect of the present disclosure is a computer program product comprising program code instructions for performing the steps of the above method, when this program is executed by a processor.

[0019] A third aspect of the present disclosure is a device, for example an internet access gateway, comprising: • a communication interface suitable for connection to an analog telephone line comprising two electrical wires; • a processor configured to test the communications interface using the method described above. DESCRIPTION OF FIGURES

[0020] Other characteristics, aims and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting, and which must be read in conjunction with the appended drawings in which:

[0021] [Fig.l] schematically illustrates a device 1 according to a first embodiment of the invention.

[0022] [Fig.2] shows voltage values ​​expected to be used by an FXS port in an off-hook state and in an on-hook state.

[0023] [Fig.3], [Fig.4] and [Fig.5] are flowcharts of steps of a method according to one embodiment.

[0024] Throughout the figures, similar elements bear identical references. DETAILED DESCRIPTION OF THE INVENTION

[0025] With reference to [Fig.l], a device 1, such as an internet gateway, comprises a first communication interface 2 with an analog telephone network A, a processor 4, and a second communication interface 6 with a digital network B, for example a WAN (Wide Area Network).

[0026] In the remainder of the present disclosure, a non-limiting embodiment will be considered in which the first communication interface 2 with the analog telephone network is, or comprises, an FXS (Foreign exchange subscriber) port.

[0027] The FXS port is suitable for being connected to an analog telephone via an analog communication line comprising two electrical wires conventionally called TIP and RING.

[0028] A function provided by the FXS port is to ensure the proper functioning of the connected analog telephone, to transmit and receive the signaling necessary for carrying out an analog communication (voltage and current supply of the telephone line, ringing signal during an incoming call, status of the loop).

[0029] The electrical communication line may thus comprise a cable suitable for being removably connected to the device 1 and to the analog telephone. This cable may comprise, for example, an RJ11 connector.

[0030] The FXS port comprises a line interface 20, or LIF, comprising two electrical contacts suitable for being electrically connected respectively to the first electrical wire and to the second electrical wire of the analog telephone line.

[0031] The FXS port further comprises a subscriber line interface circuit 22, or SLIC (Subscriber Line Interface Circuit). The SLIC circuit is configured to perform certain processing, for example an audio conversion between an analog signal coming from the analog telephone and the digital network connected to the gateway. Other processing (gains, transcoding, echo cancellation) can also be performed by the SLIC circuit or by the processor 4.

[0032] The FXS port further comprises a converter 24 configured to electrically power the other components of the FXS port (SLIC, LIF) as well as the analog communication line, and the analog telephone which is possibly connected thereto. The converter 24 is a DCDC converter, that is, it provides the analog communication line with an output direct current from an input direct electric current that it receives, and which is of different intensity. The input electric current comes from an electric current source external to the device 1.

[0033] The converter 24 is capable of generating different voltages depending on the operating mode of the FXS port. These voltages are for example higher than the general power supply voltage of the gateway provided by the external source (12 Volts in France).

[0034] In a manner known per se, an analog telephone is capable of being in an off-hook state or in an on-hook state. These state names refer to the fact that an analog telephone may comprise a base and a telephone handset comprising a loudspeaker and a microphone, the telephone handset being capable of being taken off the base or being hung up on it.

[0035] When the analog telephone is in the off-hook state, the analog telephone establishes communication with the FXS port exclusively. The telephone then receives electrical current via one of the two electrical wires of the telephone line and retransmits the received electrical current via the other electrical wire of the line, thus forming a current loop. It is then conventionally said that the telephone line is "busy" by the analog telephone. A user of the telephone is notified of the off-hook state by a dial tone. The user can then dial a telephone number to establish a telephone communication with a recipient.

[0036] When the analog telephone is in the on-hook state, no communication is established with the FXS port. No current flows through the two electrical wires of the analog telephone line.

[0037] [Fig.2] shows the voltage values ​​that are supposed to be used in the off-hook state and in the on-hook state. These voltages are negative with respect to the ground of the FXS port. These voltages are as follows: • GND: the ground reference, • Vbat: voltage supplied by the converter, • Vring: voltage between the RING electrical wire and ground, • Vtip: voltage between the TIP electrical wire and ground, • Vloop: voltage between the two electrical wires TIP and RING, • VOV_GND and VOV_BAT: predefined offset voltages allowing the transmission of audio signals, • Vcm: arbitrary reference voltage, equal to (Vtip+Vring) / 2.

[0038] The FXS port includes a memory configured to store various measurements relating to the analog telephone line. This memory is for example included in the SLIC circuit 22. These measurements include the aforementioned voltages and re- presented in [Fig.2], as well as the intensity of the following currents: • Iloop: intensity of the current flowing in the TIP and RING electrical wires in two opposite directions, which will be called “loop current” in this disclosure, • Hong: intensity of a leakage current from the TIP or RING electrical wire to ground.

[0039] The FXS port includes an internal measuring device adapted to measure the aforementioned voltages and current intensities, and to regularly update the information stored in the memory, for example periodically, so that the measurements stored in these registers at a given time strive to reflect the state of the analog telephone line at that given time.

[0040] The memory comprises for example 32-bit registers, each register storing one of the aforementioned measurements.

[0041] For example, the least significant bit of a memory register for a voltage is 931.323 9 Volts. For example, the least significant bit of a memory register for a current is 1.6769 Amperes.

[0042] The memory is also configured to store a boolean estimating whether the FXS port is in an off-hook state or in an on-hook state (the value of this boolean is automatically adjusted by the SLIC circuit). This information indicates that: • the FXS port is in the off-hook state when the FXS port considers itself to be connected via the analog telephone line to an off-hook telephone device (in other words, when the FXS port considers the analog telephone line to be busy), and • the FXS port is in the on-hook state when the FXS port believes that it is not connected to any off-hook telephone device (in other words, when the FXS port believes that the analog telephone line is not busy).

[0043] In practice, this boolean can be coded on a single bit.

[0044] The processor 4 is configured to execute a computer program performing various functionalities, including controlling the operation of the FXS port. For this, the program comprises or is combined with a dedicated driver of the FXS port, this driver comprising various code functions.

[0045] Certain driver code functions pass commands to the FXS port requesting the FXS port to perform tests on the analog telephone line, for example, tests defined in the GR-909 standard cited in the introduction to this disclosure. These tests are set forth in sections 12.4.6 (Interface to Embedded Loop Testing Systems) and 12.4.7 (Generic Testing Interface) of the GR-909 specification.

[0046] Other driver code functions allow read access to the in- formations stored in the FXS port memory.

[0047] The computer program is itself stored in a memory 8 of the device 1, external to the FXS port.

[0048] We will now describe a method for testing the FXS port implemented by the processor 4, when this processor 4 executes the aforementioned computer program.

[0049] With reference to [Fig. 3], the processor 4 detects in a step 100 a change in the state of the FXS port. There are two possible state changes: a hook-up (the FXS port changes from the on-hook state to the off-hook state) or a hook-up (the FXS port changes from the off-hook state to the on-hook state).

[0050] This detection step 100 can be carried out for example by accessing in reading the register of the memory of the FXS port storing the boolean indicative of its state, and this repeatedly over time, for example periodically. A reading of a zero followed by a 1 or a 1 followed by a zero reflects a change of state.

[0051] If the processor 4 detects a dropout, then the processor 4 collects measurements acquired by the FXS port, by accessing in reading the corresponding registers of the memory of the FXS port. The measurements relate to at least one of the following physical quantities: • the Vbat voltage supplied by the converter, • the Vloop voltage between the two electrical wires, • the intensity Iloop of the loop current flowing in the first electric wire or in the second electric wire, • the Hong intensity of the leakage current.

[0052] For each physical quantity measurement collected, the processor 4 checks for a correspondence between the collected measurement and a nominal value of the physical quantity. A nominal value is an expected value for the physical quantity considered, reflecting normal operation.

[0053] The processor 4 can verify such a correspondence by comparing the measurement with the nominal value, the latter having been stored by the device 1 beforehand. If it is found that the difference between the measurement and the stored nominal value is less than a threshold (the threshold being able to be equal to zero or different from zero to reflect a tolerance margin), then it is considered that the measurement corresponds to a nominal value. If it is found that this difference is greater than the threshold, it is considered that the measurement does not correspond to a nominal value.

[0054] Alternatively, the processor 4 can verify such a correspondence by comparing the measurement with an abnormal value stored by the device 1 beforehand (this value is said to be abnormal because it represents an abnormal situation). If it is found that the difference between a measurement and the stored abnormal value is less than a threshold (the threshold being able to be equal to zero or different from zero to reflect a margin of tolerance), then it is considered that the measurement does not correspond to a nominal value. If it is found that this deviation is greater than the threshold, it is considered that the measurement corresponds to a nominal value.

[0055] If the verification of the measurements reveals that all the measurements correspond to nominal values, then the situation is considered normal, and the processor 4 implements a cyclic test processing which is represented in [Fig.3] by block A. This cyclic test processing will be detailed later.

[0056] Preferably, the measurements are verified in two successive verification steps 102 and 104.

[0057] In the first verification step 102, the processor 4 checks whether the measured voltage Vbat corresponds to a non-zero nominal voltage value stored by the device 1. The processor 4 can for example use a tolerance margin, for example 5%.

[0058] If the measured voltage Vbat does not correspond to the nominal value (i.e. the difference between Vbat and the nominal value is greater than the tolerance margin), then the method moves to block B. Block B is representative of an error case which triggers the implementation of certain steps of the method which will be described later.

[0059] If, on the contrary, the measured voltage Vbat corresponds to the nominal value, then the processor 4 moves on to the second verification step 104, during which the processor 4 checks whether the other measurements collected (Vloop, Iloop, Hong) correspond to nominal values.

[0060] An abnormal value for the Vloop voltage is a zero value. Indeed, such a zero value would reflect a short circuit between the first electrical wire and the second electrical wire. Under these conditions, the processor 4 considers that the measured Vloop voltage is nominal if and only if the Vloop voltage is in absolute value greater than a threshold constituting the chosen tolerance margin (equal to zero or close to zero).

[0061] A nominal value for the loop current intensity Iloop is a predefined non-zero value Iref stored by the device 1. Under these conditions, the processor 4 considers that the measured intensity Iloop is nominal if and only if a difference between Iloop and this predefined non-zero value is less than a threshold constituting the chosen tolerance margin (equal to zero or close to zero). Otherwise, a resistance fault probably occurs.

[0062] A nominal value for the leakage current Hong intensity is a zero value. Indeed, a non-zero value would reflect a current leak from the analog telephone line to ground. Under these conditions, the processor 4 considers that the measured Iloop intensity is nominal if and only if Iloop is in absolute value lower than a threshold constituting the chosen tolerance margin (equal to zero or close to zero).

[0063] Ultimately, the Vloop, Iloop and Hong measurements correspond to nominal values ​​if the following relationships are all respected, within a tolerance margin:

[0064] Vloop = 0

[0065] Iloop Iref

[0066] Hong ± 0

[0067] As indicated previously, the method proceeds to block A if all these relationships are respected.

[0068] If on the contrary at least one of the following relationships is not respected, otherwise if at least one of the measurements Vloop, Iloop and Hong does not correspond to a nominal value, then the processor 4 commands, in a step 106, the implementation by the FXS port of a complementary test of the telephone line, so as to collect diagnostic data complementary to the measurements.

[0069] The complementary test includes at least one of the following tests, defined by the GR-909 standard. Test name GR-909 translated into French Test name in original language (English) Additional data collected #1 Hazardous Potential and Foreign Electrical Motive Force test Residual voltage measured between the TIP and RING wires Residual voltage measured between the TIP wire and ground Residual voltage measured between the RING wire and ground #2 Resistive Faults Test Impedance measured between the TIP and RING wires Impedance measured between the TIP wire and ground Impedance measured between the RING wire and ground #3 Receiver Off Hook test Specific impedance test: an off-hook receiver has a variable impedance depending on the voltage between the TIP and RING wires

[0070] For example, the complementary test may first include tests #1 and #2, and not understand test #3 only if tests #1 and #2 do not reveal a fault. Test #3 is actually an impedance consistency test to check for the presence of an off-hook analog phone. This test is able to differentiate between an off-hook phone and an impedance of similar value.

[0071] Tests #1, #2 and #3 can be performed in any order. For example, the supplemental test may include test #3 first and then tests #1 and #2.

[0072] Once this additional data has been collected, the processor 4 emits an alarm (step 108).

[0073] This alarm can be communicated to a user of the device 1, for example in the form of a message displayed on a display screen of the device 1. Alternatively or additionally, the alarm is transmitted to a maintenance server via the first communication interface. In this way, the user and / or the maintenance organization of the device 1 is informed of the existence of a malfunction of the analog telephone network. The additional data collected characterize and quantify this malfunction. This additional data can in fact indicate the location of the malfunction (at the FXS port, at the analog telephone, or at the analog telephone line) and / or quantify the malfunction (for example via the impedance measurements collected).

[0074] Up to now, steps performed by the processor 4 when a stall is detected have been described.

[0075] When the processor 4 detects, on the contrary, a hang-up (transition of the state of the FXS port from the off-hook state to the on-hook state), the processor 4 implements the following steps.

[0076] In a step 110, the processor 4 collects the Vloop voltage measured by the FXS port, and checks whether this Vloop voltage is nominal (in accordance with the rule described previously). If yes, the situation is normal, and the method moves to block A. Otherwise, the processor 4 implements step 112.

[0077] In step 112, the processor 4 accesses information stored in the memory of the FXS port, the information indicating whether the communication interface has received a command to power the analog telephone line or not. If yes, the method proceeds to block B. Otherwise, the method proceeds to block C.

[0078] Unlike block A, which reflects a normal situation, blocks B and C reflect two abnormal situations to different degrees.

[0079] We will now detail the cyclic test processing materialized by block A in [Fig.3]. This cyclic test processing includes the following steps, represented in [Fig.4].

[0080] In a step 200, the processor 4 detects that the state of the FXS port (on-hook state or off-hook state) is maintained for a predefined duration. The predefined duration can be greater than one hour, or even greater than 6 hours, or even greater than 12 hours, or even greater than 24 hours. In all cases, the predefined duration is significantly greater than the reading period of the Boolean indicating this state.

[0081] If the processor 4 detects that the FXS port remains in the off-hook state for the predefined duration, then the processor 4 proceeds to step 202.

[0082] In step 202, the processor 4 orders a complementary test on the analog telephone line, so as to collect the complementary diagnostic data, in accordance with step 106 described above.

[0083] In step 202, the processor 4 further checks whether this additional diagnostic data reveals a fault in the analog telephone network or not. Such a fault may occur at the FXS port, at the analog telephone, or at the analog telephone line between the two.

[0084] If the diagnostic data reveals a fault in the analog telephone network, the processor 4 implements a step 204 of transmitting an alarm, which may be identical to step 108.

[0085] If the diagnostic data does not reveal a fault in the analog telephone network, then the processor 4 returns to block A. The steps described previously can then be implemented again upon detection of a maintenance of the state for the predefined duration.

[0086] If the processor 4 detects in step 200 that the FXS port remains in the on-hook state for the predefined duration, then the processor 4 implements steps 210, 212 identical to steps 110 and 112 according to the same logic and the same consequences as in the case of detection of a hang-up described previously. The implementation of steps 210, 212 can thus result in block A, B or C depending on the case.

[0087] We will now detail the steps implemented by the processor 4 when the method is in block B with reference to [Fig.5] (we recall that this situation occurs if the processor 4 comes to the conclusion that the FXS port has not received a power supply command to power the analog telephone line).

[0088] In this situation, the processor 4 controls the FXS port so that the FXS port powers the analog telephone line (step 300). For this purpose, the processor passes an appropriate power command to the FXS port.

[0089] Next, in a step 302, the processor 4 collects new measurements for the physical quantities discussed previously, then checks the correspondence of each new measurement with a nominal value. Thus, step 302 corresponds to steps 102 and 104 shown in [Fig.l].

[0090] If the verification carried out during step 302 reveals that all the new measurements have nominal values, then the method moves to block A (normal situation). If the verification reveals that at least one of the new measurements does not have a nominal value, then the method moves to block A (normal situation). nominal, then the method proceeds to step 304.

[0091] In step 304, the processor 4 commands a restart of the FXS port converter, using an appropriate command.

[0092] Next, in a step 306, the processor 4 collects new measurements for the physical quantities discussed previously, then checks the correspondence of each new measurement with a nominal value. This step is identical to step 302.

[0093] If the verification reveals that all the new measurements have nominal values, then the method proceeds to block A (normal situation). If the verification reveals that at least one of the new measurements does not have a nominal value, then the method proceeds to step 308.

[0094] In step 308, the processor 4 commands a hardware reset of the FXS port (“hard reset” in English). The processor 4 can also restart the program that it is executing, or at least a module of the program using the FXS port, for example a module for managing communication between the telephone network and a VOIP service accessible via the digital network.

[0095] Next, in a step 310, the processor 4 collects new measurements for the physical quantities discussed previously, then checks the correspondence of each new measurement with a nominal value. This step is identical to step 302.

[0096] If the verification reveals that all the new measurements have nominal values, then the method proceeds to block A (normal situation). If the verification reveals that at least one of the new measurements does not have a nominal value, then the processor 4 issues an alarm in a step 312 (which may be identical to step 108).

[0097] We will now detail the steps implemented by the processor 4 when the method is in block C (we recall that this situation occurs if the processor 4 comes to the conclusion that the FXS port has received a power supply command to power the analog telephone line).

[0098] In this case, the method goes directly to the step of restarting the converter 304, then implements the steps subsequent to the step of restarting the converter described in case B.

[0099] We will now detail an example of implementation of the process with nominal values ​​finding application in France, for example.

[0100] The FXS is configured to provide a quiescent voltage of 47 Volts and an off-hook current of 36 mA. The VOV_GND and VOV_BAT offsets are set to 5.25 Volts.

[0101] Upon detection of a stall, the processor 4 collects the following measurements: Vbat = 26.83 Volts, Vtip = 5.47 Volts, Vring = 22.46 Volts.

[0102] Here, Vbat seems correct since Vbat > Vtip, but we notice that we do not have the relation Vbat = Vtip+ VOV_BAT.

[0103] Processor 4 then checks the other measurements. It finds that: • Vloop = Vtip - Vring = 19.99 Volts (which is different from 0 Volts). • Iloop = 35.46 mA; with a tolerance of 5%, we have the loop current preset (36 mA). • Hong = 0.31 mA; with a margin of error, this value can be considered zero.

[0104] We are thus in a situation where all the collected measurements have nominal values; the method therefore moves to cyclic processing (block A). After waiting for the predefined duration, the processor 4 notes that the FXS port has remained in the off-hook state. The processor 4 then implements the additional test. In particular, test #3 “Receiver Off-Hook” indicates that the off-hook state perceived by the FXS port is not caused by an analog telephone. Under these conditions, the processor 4 implements test #2, thus making it possible to collect the following impedances: • Impedance between TIP wire and ground: 2000000 ohms • Impedance between the RING wire and ground: 2000000 ohms • Impedance between TIP and RING wires: 220 ohms.

[0105] These values ​​reveal the existence of a fault, because the impedance measured between the TIP and RING wires is lower than that of an ordinary station in working order (impedance between 400 and 600 ohms). The alarm is therefore triggered.

[0106] The processor 4 is capable of executing instructions loaded into the memory 8 from a “Read Only Memory” or “ROM” memory, an external memory (such as a memory card such as a “Secure Digital” or “SD” card), a storage medium (such as a hard disk), or a communication network. When the device 1 is powered up, the processor 4 is capable of reading instructions from the memory 8 and executing them. These instructions form a computer program causing the implementation, by the processor 4, of all or part of the behaviors, processing, algorithms and steps described here.

[0107] Thus, all or part of the algorithms, processing operations and steps described herein may be implemented in software form by executing a set of instructions by a programmable machine, such as a DSP (Digital Signal Processor) or a microcontroller or a processor. All or part of the algorithms, processing operations and steps described herein may also be implemented in hardware form, or in the form of a combination of a hardware form and a software form, by a machine or a component (chip), such as an FPGA (Field-Programmable Gate Array) or an ASIC (Application-Specific Integrated Circuit). Thus, the device 1 comprises electronic circuitry adapted and configured to implement the behaviors, processing operations, algorithms and steps described herein.

Claims

Claims

1. A method of testing a communication interface connected to an analog telephone line comprising two electrical wires, the method comprising the following steps: detecting (100) a change in state of the communication interface between an off-hook state and an on-hook state; if it is detected that the change of state is from the on-hook state to the off-hook state, collection of measurements acquired by the communication interface, the measurements relating to at least one of the following physical quantities: • a voltage supplied (Vbat) by a converter of the communication interface, • a voltage (Vloop) between the two electrical wires, • an intensity of a loop current (Iloop) circulating in one of the two electric wires, • an intensity of a leakage current (Hong) from one of the two electrical wires to a ground of the communication interface; verification (102, 104) of correspondence of the measurements with respective nominal values; if the verification reveals that all measurements have nominal values, implementation of a treatment comprising the following steps: • detection (200) of maintaining the state of the communication interface for a predefined duration; • if it is detected that the communication interface remains in the off-hook state for the predefined duration, command (202) of an additional test on the telephone line by the communication interface, so as to collect diagnostic data complementary to the measurements; • if the additional diagnostic data reveals a fault in the analog telephone network, transmission (204) of an alarm; • if the additional diagnostic data do not reveal a fault on the analog telephone line, repeat the treatment.

2. A method according to the preceding claim, further comprising the following steps: • if the verification reveals that at least one measurement among the voltage (Vloop) between the two electric wires, the intensity of the loop current (Iloop) and the intensity of the leakage current (Hong) does not have a nominal value, command (202) of the additional test on the telephone line by the communication interface, so as to obtain the diagnostic data complementary to the measurements, and emission of the alarm if the diagnostic data reveals a fault in the analog telephone network.

3. A method according to any preceding claim, comprising the following steps performed if it is detected that the change of state is from the off-hook state to the on-hook state or if the communication interface remains in the on-hook state, • collection of a voltage (Vloop) between the two electrical wires acquired by the communication interface; • checking (110, 210) the voltage (Vloop) between the two electrical wires, so as to determine whether the collected voltage has a nominal value; • if the voltage (Vloop) between the two electric wires has a nominal value, implementation of the treatment; • if the voltage (Vloop) between the two electrical wires does not have a nominal value, access (112) to information stored by the communication interface, the information indicating whether the communication interface has received a command to supply power to the analog telephone line or not; • if the information indicates that the communication interface has not received a power supply command, then command (300) of the communication interface so that the communication interface supplies the analog telephone line; • if the information indicates that the communication interface has received a power supply command, command (304) to re converter start.

4. Method according to the preceding claim, further comprising the following steps implemented after the control of the communication interface so that the communication interface supplies the analog telephone line: • collection of new measurements acquired by the communication interface, the new measurements relating to at least one of the physical quantities; • verification (302) of correspondence of the new measurements with the respective nominal values; • if the verification of correspondence of the new measurements reveals that all the new measurements have nominal values, implementation of the processing; • if the verification of correspondence of the new measurements reveals that at least one of the new measurements does not have a nominal value, command (304) to restart the converter.

5. Method according to any one of claims 3 and 4, further comprising the following steps implemented after the command (304) to restart the converter: • repeating (306) the steps of collecting and verifying new measurements; • if the repetition (306) of the steps of collecting and verifying new measurements reveals that all the new measurements have nominal values, implementing the processing; • if the repetition (306) reveals that a new measurement does not have a nominal value, command (308) to hardware reset the communication interface.

6. Method according to the preceding claim, further comprising the following steps implemented after the hardware reset command of the communication interface: • second repetition (308) of the steps of collecting and verifying new measurements; • if the second repetition (308) reveals that all the new measurements have nominal values, implementation of the processing; • if the second repetition (306) reveals that a new measurement does not have a nominal value, emission (312) of an alarm.

7. A computer program product comprising program code instructions for executing the steps of the method according to any one of the preceding claims, when this program is executed by a processor (4).

8. Device (1), for example an internet access gateway, comprising: • a communication interface (2) suitable for being connected to an analog telephone line comprising two electrical wires (TIP, RING); • a processor (4) configured to test the communication interface (2) using the method according to any one of claims 1 to 7.

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