JP2001519984A - Monitoring method of ISDN link - Google Patents

Abstract

(57) [Summary] Communication signals (voice and / or data) are transmitted to a subscriber via a B channel of an integrated services digital network (ISDN) link connected to a public switched telephone network (PSTN) including an SS7 signaling system. Provided. The monitoring system extracts data from subscriber signaling messages traversing the D channel of the ISDN link and from messages traversing the SS7 signaling system, and generates further monitoring data by measuring the parameters of the communication signal on the B channel. . These data are correlated to derive information that assists in managing the communication services provided over the ISDN link.

Description

DETAILED DESCRIPTION OF THE INVENTION                         Monitoring method of ISDN linkTechnical Field of the Invention   The present invention collects data from an ISDN (Integrated Services Digital Communication Network) Related to monitoring systems.Background of the Invention   IDSN was created to provide customers with digital access to public networks. Different services can be sent over different ranges of bandwidth. You. Narrowband ISDN is widely deployed worldwide. Broadband ISD N (B-ISDN) is just getting deployed and tested with multiple operators At the target stage. The networks that operators actually have to manage , Existing digital and analog networks, narrowband ISDN, wideband ISDN , Internet technology, and other technologies. specific Services are probably resources from multiple of these different networks (needs Some examples of different resources and techniques are shown in FIG. 2). Become. This poses a significant problem for end-to-end management of the service. The monitoring system described in this document addresses many of these problems.Disclosure of the invention   The method for monitoring an ISDN link provided by one aspect of the present invention is a first-order method. Monitor the subscriber signaling message on the ISDN D channel at the first ISDN B channel for deriving visual data and relating to said ISDN D channel The communication traffic flowing to and from the first location is monitored at the first Deriving data and correlating the first and second monitoring data. Have   In some cases, a communication network coupled to the ISDN link (eg, Signaling messages (e.g., S) on a signaling link in the public switched telephone network-PSTN S7 protocol message) to derive third monitoring data, Combining the third monitoring data with at least one of the first and second monitoring data It may be desirable to correlate. Another option is the second position Monitors signaling messages and communication traffic on the ISDN link at Correlating the monitoring data resulting from the first and second monitoring data Is mentioned.   A method for monitoring an ISDN link provided by another aspect of the present invention comprises: Monitor the subscriber signaling message on the D channel to derive first monitoring data; Further on a signaling link in a communication network coupled to the ISDN link To monitor the signal message (eg, SS7 protocol message) Deriving data and correlating the first and second monitoring data. It has a loop.   A monitoring device for an ISDN link provided by yet another aspect of the present invention comprises: Monitor subscriber signal messages on the ND channel to derive first monitoring data A first device at a first location for connection with the ISDN D channel. Monitoring the communication traffic passing through the ISDN B channel to A second device at the first location from which the data is derived, and the first and second monitoring data. Correlator connected to the first and second devices for receiving and correlating data It is provided with.   A monitoring device for an ISDN link provided by another feature of the present invention is an ISDN link monitoring device. Monitoring the subscriber signaling message on the D channel to derive first monitoring data; A first device and a communication network coupled to the ISDN link. Yet another signaling message on the signaling link (eg SS7 protocol message) A second device for monitoring and deriving second monitoring data; Connected to the first and second devices for receiving and correlating the monitoring data of And a correlation device.BRIEF DESCRIPTION OF THE FIGURES   Next, a specific example of the method and apparatus according to the present invention for monitoring an ISDN link is described. This will be described with reference to the accompanying drawings. In the drawing,   FIG. 1 shows a distributed ISDN monitoring system,   FIG. 2 shows a log that can be correlated to create an end-to-end service record. Shows examples of local loop and core network probe measurements,   Figure 3 shows the architecture for monitoring ISDN and SS7 signaling systems together. An example of a tea is shown.Best mode of practice of the invention and industrial applicability   The illustrated distributed monitoring system collects data from the ISDN and rearranges the data. Real-time correlation and real-time observation of services on the network Is what makes it possible. The data is used for troubleshooting, monitoring, and security. Planning, network planning, providing accounting information to customers, fraud detection Can be used for various purposes such as billing, marketing information, etc. . The monitoring system comprises an Internet Protocol (IP) network. Used to monitor a large number of ISDNs that may be interconnected by other technologies. Can be. Part of such ISDN shall consist of older technologies such as analog. It is also possible.   Reference is now made to FIG. The probe shown is part of a distributed monitoring system. And a link monitor (eg similar to existing protocol analyzers) Technology) or on network elements (nodes, switches, etc.) Can be implemented as software and hardware. The distributed monitoring system The stem includes the probe, standard computer, and communication components, and It is built from dedicated software that provides the purpose. Dedicated software The main function of the network is to correlate data from the different probes Records of calls, transactions, and other services that occur on or Is to provide real-time tracking. Hewlett-Packard acceSS7 system Is an example of a distributed monitoring system, which implements part of the system described above Available for:   According to the invention, the monitoring of the local loop is also dependent on the subscriber signal and the service itself. (Eg, Primary Rate Access (PRA) or Basic Rate Access) Access (BRA: Basic Rate Access) content of B channel of ISDN) A local loop or core network (FIG. 2). Data from any probe covering all technologies (E.g., any local loop loop at one end of the service). Data from probes about the protocol and any core network protocols Data from the probe about the service and any local Data from probe for loop protocol).   The architecture of the monitoring system is shown in FIG. The figure shows the SS7 network and And a probe that passively monitors both the PRA ISDN and PRA ISDN. This SS The 7 passive monitoring probe is, for example, that of the Hewlett-Packard acceSS7 system. It is possible. ISDN primary rate access probes, for example, Protocol analyzer (eg, Hewlett-Packard 37900D Signaling Test Set) It is possible to construct using the same technology as in the case.   According to the present invention, a distributed monitoring system can be used with any combination of these probes. Real-time data from the application can also be correlated. This This includes, for example, the D and B channels of the ISDN PRA and the SS7 A signal unit is included.   The invention relates to other protocols and technologies in access networks. It is possible to apply. An important example is the remote digital terminal To integrate multiple different local loop technologies into a common interface It is mentioned. Supported local loop technologies are traditional analog Connection, ISDN primary and base rates, various copper-pair based High-speed digital subscriber loop technology (eg, ADSL, HDSL), "Fiber In ・ Fibre in the Loop ”and wireless technology. ITU-T V5 specification and Bel lcore GR-303 series specifications are used to aggregate subscriber loop technology It is an example of an architecture. Digital terminals and local switches (eg V5 or The probe that monitors the connection between the GR-303 protocol) uses a protocol such as HP37900D. It can be built using technologies already available in the Narizer product. The probe Determines the signaling protocol on the connection and uses the ISDN monitoring architecture shown in FIG. The transport channel can be monitored in the same manner as the keyer. This data source is For the following description, as part of a distributed monitoring system Should be considered. Service usage data is obtained from this source It can be obtained in a similar way, but with a wider range of subscriber loop technologies. Can be obtained.   For the sake of convenience, the invention will be basically described with narrowband ISDN and its associated B (carrier) channel. The channel and the D (data) channel will be described. However, in this case A term is in its scope (regardless of whether the term conventionally means it) ) Features similar to broadband ISDN, such as asynchronous transfer mode (ATM) systems It is to be understood that a channel having   In the broadband ISDN, the D channel corresponds to the signal channel (Signalling Channel). For unrelated mode signals, Are virtual path identifier (VPI) = 0 and virtual channel identifier (VCI) = 5. In the case of a related mode signal, use the related signal. There is a separate signaling channel for each virtual path that exists. This signal channel is virtual It has the same VPI as the path, and has VCI = 5.   In the broadband ISDN, the B channel corresponds to a dynamically designated virtual channel. Channel (also called switched virtual circuit or SVC) ), Wherein the dynamically specified virtual channel transmits the message on the signaling channel. Is used to transmit signal traffic between two communicating terminals. is there. It captures and decodes related signaling messages on the signaling channel. (This will be described in more detail later). Generate service record   This section describes the field types in various cases of service records And explain how a distributed surveillance system provides the necessary data . The service record is generated for each use of a specific service. This calls It is a generalization of a record and is generated by a current switch. service Is usually defined from the user's point of view. Services are actually, for example, It may involve a call or a transaction. Service records described in this document The code uses SS7 and ISDN signaling information for such different calls. Provide single service record by correlating launch and transaction together Is what you do. 1. Caller information   Caller information can be derived from data flowing over the ISDN link It contains all the information about the caller, so link monitoring probes can It can be used. Typical information includes calling number, ISDN Subaddress information, caller name, X.25 or frame relay address, other network Network address, and any numbers or addresses associated with the bill. You.   This information may be sent at the originating or terminating end or both at the ISDN D channel. From the call setup message above and / or on any SS7 link It can be derived from the call setup message. For more information, Can be derived from ISDN B channels for certain services, such as It is possible. In this case, the header of the frame includes the address information. SS Intelligent network that flows over 7 links as part of specific service usage It is also possible to derive additional information from the service message. Specific sir ISDN B or D channel of intelligent peripheral with use of service It is possible to derive further information by looking. 2. Callee information   Same as caller information, but with the caller replaced by the called party. 3. Network routing information   Network routing information is used to provide this particular service usage. It contains information about the network resources used. The following is provided It is an example of data that may have been performed.       The ISDN links and channels used       -SS7 links and nodes used       -Used trunk       -The intelligent network node used;       Each of these uses is time-stamped, and the use sequence and Properties are indicated.   These data are based on item 1. In the same manner as described in it can. 4. Intelligent network service information   Intelligent network service information is used for specific service usage. Information about intelligent network services You. The following are some examples of data that may have been provided.         -Caller name distribution information         − Local number portability information         -Call transmission information         − Interactive voice response information when using intelligent peripherals         -800 service       The information includes a timestamp, duration, and nature of the usage.   These data are described in item 1. Can be derived in the same manner as described in Wear. 5. Service status and termination information   Service status and end information occurs during service start and service Include time-stamped information about status changes and service termination. And it is possible. The termination information should include a reason for termination.   These data are based on item 1. Can be derived in the same manner as described in . In particular, paging clear message on SS7 link and ISDN D channel Can provide details of the reason for terminating the call. 6. B channel analysis to distinguish between fax or data and voice   As part of the service record generation process, The channel can be identified from the signaling message on the corresponding D channel. Capture data from B channel to probe that monitors the link carrying B channel Can be ordered to do so. Analysis of the spectrum of this captured data It can be used to identify the type of service being transmitted on the B channel. It is possible. Using this, fax or data call and sound Voice calls can be distinguished. Check for changes in the type of service being used. Command the probe to periodically sample the B channel for It is possible. 7. Tone on the B channel to identify additional dialed data analysis   Multi-frequency tones that can provide more information about the call (eg, Analyze data captured from the B channel to identify DTMF) It is also possible to instruct the probe. This is after the first call connects Can be used to identify additional digits dialed by the subscriber . Such digits are generated by the surveillance system for the call. Service records. There are two digits Also used to identify fax calls from signals between other facsimile machines. It is possible to 8. Service type   Service types can include information about the following types of services: is there.         voice         modem         fax         video         X.25         Frame relay         ATM (asynchronous transmission mode)         LAN interconnect   These data are based on item 1. Can be derived in the same manner as described in . In particular, the call establishment message on the ISDN D channel Provide information about IP. The message is included in the ISDN D channel signal. And correlating with data obtained from the identified ISDN B channel. it can. 9. Service quality information   The provided quality of service information is based on the service indicated in the service type field. Determined by screws. Some examples of what can be offered for a particular service These are listed below.   Voice quality is mainly indicated by bit error rate and delay. These parameters Provides signal information to identify the ISDN B channel carrying the audio signal. It is measured using a passive monitoring system. B channel identified Compare the bit streams from each of the And the bit error rate can be derived. This means that one of the intermediate networks Packet or frame based and delivery time cannot be guaranteed It is particularly important when the object is an object (eg, IP protocol or ATM).   Video, modem and fax qualities can be derived in a similar manner.   Data oriented protocols (X.25, frame relay, ATM, and LAN Connection) requires additional data. This is also SS7 from the probe or Identify ISDN channels that carry the protocol using ISDN signaling data By doing so, it is possible to measure. Packet loss, retransmission, CRC error To estimate parameters such as error, throughput, and packet delay Existing protocol analysis techniques can be used. 10. Service usage information   The usage time data provided by the distributed monitoring system depends on the specific service. It is determined. The following are some examples.   Voice, video and fax services are available for the duration of the call and Requires bandwidth.   Data-oriented services are based on total bits, frames, and packets for each direction. Need such data. The data is collected at regular time intervals for the service period. Can be provided. The data is also stored in a data protocol with additional addresses. If you have traffic information (IP address, etc.), divide it into traffic matrix It is also possible. The data corresponds to item 9. Similar to the description of Can be derived as follows. 11. Security information   Attempts to gain unauthorized access to resources as a specific example of service usage Is mentioned. Service records contain information that can indicate this type of activity. No. The service record indicates the duration of the call, the manner in which the call ends, and It may include information about the details of the service provided.   One example is when a modem is repeatedly used and a different password is tried. Case. The ISDN B channels used are SS7 and ISDN signals. Identified from the data. The probe then reads data from the ISDN B channel. Once extracted, the system can determine the modem protocol to identify the action.   The above example focuses primarily on narrowband ISDN. However, this The same concept applies to broadband ISDN and ATM. Q.931 Protocol Variants of these standards are based on the user network interface signals (U NI) and inter-network interface signals (NNI) . They can be monitored in the same way as above, A service record is generated from a series of messages that control the operation. Channel The concept is replaced by the concept of virtual path and virtual channel. However, The virtual path and virtual channel associated with a given call are identified from the signaling message Monitor the links carrying these virtual paths and channels The probe that captures the data associated with the call and generates Order to provide the same analysis as in the narrowband case for inclusion in service records. It is possible to order. Real-time update when using the service   The data in the service record described in the previous section is Collected in the system. When those data become available, Provided in real time on a connected computer at a remote location. Distributed Surveillance system users apply filtering criteria to the information described in the previous section. You can choose the service usage that requires real time update You. Use   Using data from service records or real-time service updates described above The following applications can be implemented. Using data from other sources, it It is also possible to increase the efficacy of these applications. A. Service quality and service level agreement   Service offering for a given customer's service using the service record described above Can provide quality information. Is this a service level agreement? That can be used to track Can be provided to customers. This is a regular report Or can be provided in real-time using the real-time update described above . B. Audit and troubleshoot network operations   Service records and real-time updates indicate service or network failures. Can be used to identify harm. The information can also be used to troubleshoot the fault. It can also be used for marketing. C. Fraud detection   Service records and real-time updates indicate the potential of a network or service. It can be used for identifying illegal use. Expensive to indicate abuse Service overuse, abnormal call termination, and access to services Includes repeated failures. Decentralized monitoring systems are a potential high-risk user Can be used to track service usage in real time. D. Security and hack detection   A potential security threat is the repeated failure to access a service. Can be identified. The threat can also be attributed to customer premises equipment (Customer Premises Access to delicate services such as equipment (CPE) maintenance ports May be indicated by the success of the This type of data includes service records and It can be obtained from real-time updates. E. FIG. Invoice creation data   Service records are billing dependent on fields in the service record Can be used as a base for This allows you to actually provide A bill can be created based on the quality of service provided. This is also Resources on the network, such as intelligent peripherals and databases Enables the creation of invoices that reflect the nature and generation of resources used. F. Use of B channel data for billing or billing verification   In some countries, the regulatory requirements for Telecom operators are: Calls that carry voice have a different pricing system than calls that carry data. Need to do that. In addition, access charges between operators are It depends on whether it is voice or data, and if it is voice, It also needs to be determined by the final destination. For monitoring systems The service record generated from the above item 6. And 7. B channel described in In these cases (and similar situations) using data derived from the Can be used to determine the amount charged. G. FIG. Customer accounting data   Detailed service usage information in the service record is for customer internal accounting Can be provided to customers. The information includes ISDN B and D Trough for packet and frame based protocols derived from channels Information is included. H. Network planning for customers and telecom operators   Service records are submitted to the network planning departments of operators and customers. Provide detailed information on the use of available network resources It is possible. SS7 signaling network and voice trunk network 1. Includes data from both SS7 signaling and trunk networks Monitoring system for providing call records   Monitoring systems such as Hewlett-Packard's acceSS7 system use the SS7 network. Call (or service) by monitoring the above message sequence Can be used to generate records. This surveillance system sounds Can be extended with a probe that monitors the trunk carrying the voice path . Trunks that carry the voice path of a particular call are not included in the SS7 message. Field (usually the TCIC in the IAM). Then Real-time analysis or subsequent analysis of the probe connected to the trunk Data can be ordered to be captured from the trunk for analysis. 2. Analysis of "voice path" to distinguish between fax or data and voice   As part of the service record generation process, the The rank can be distinguished from the signaling message on the corresponding SS7 network. Wear. Capture data from the trunk to probes monitoring the trunk Can be ordered to Spectral analysis of the captured data is called Can be used to identify the type of service supported during delivery You. This is useful to distinguish voice calls from fax or data calls. Can be used. Regularly sample trunks to determine which services are in use. The probe can be instructed to check for type changes. 3. Tone in the "voice path" to identify additionally dialed data analysis   A multi-frequency tone (eg, D To identify the TMF) and analyze the data captured from the trunk. It is also possible to instruct the slave. This is done after the first call is connected. Can be used to identify additional digits dialed by the entrant It is. These digits are generated by the surveillance system for the call. It can be added to the service record to be added. This is also two fac Can also be used to identify fax calls from inter-similiar signals It is. 4. Use of "voice route" for billing   In some countries, regulatory requirements for telecom operators may require that voice Requires that the calling call be at a different rate than the data-carrying call are doing. Also, the access fee between operators depends on whether the call is voice or data. And if the call is audio, the final destination of the call Therefore, it is necessary to be determined. Services generated by monitoring systems The record uses the data derived from the "voice path" as described above, In the case of (and similar circumstances) Can be. Example of B-ISDN using ATM   An embodiment relating to a broadband ISDN using ATM will be described in more detail.ATM infrastructure including UNI and NNI signals and potential monitoring points Account :   The probe is connected to the user network of the network-to-network interface (NNI). Monitors ATM links capable of supporting data interface (UNI) I do. This can be a public interface, personal interface, or carrier Can be an inter carrier interface, For more information on the interfaces of ITU-T, see section 4.1 of ITU-T standard Q.2931. It is described in “B-ISDN Application Protocols For Access Signaling”.   A probe monitors one or more links in an ATM network and It has the ability to correlate data between these links as shown in FIG.Description of ATM probe including passive optical tap :   The ATM probe is connected to an optical power splitter physically inserted into the optical link. Monitor links more. This ensures that the probe does not change the transmission on the link Is guaranteed. The ATM probe provides a fraction of the optical power (typically 10%). Obtain and provide a copy of the ATM power being carried by the link over the optical power Use to ATM probes are hardware (eg, processors, ATM and I / O interfaces) and the ATM protocol carried on the ATM layer With software that allows decoding of ing.A service record (S) for a switched virtual circuit (SVC, also called a call) R) Generation : Step 1. Configuration of service record collection system   Specify collection criteria for the monitoring system. This is the system administrator Data execution or programmatically implemented by a software application. It is possible to do. The collection criteria meet a set of filtering criteria SETUP message (“Private Network-Network Interface Specification” Ver.1. 0 (PNNI 1.0) section 6.3.1.6 (ATM Forum af-pnni-0055.000, 1996 Should be ordered to conduct monitoring to provide notification of It is possible to include a list of lobes. The filtering criteria is the SETUP menu Identify the characteristics of the fields in the message. These are typically the SETUP messages Page caller or called party number information element (see section 4.5.11 / 1 of Q.2931 above) (See 3). E.164 address Addresses are the most common address types, but other types of addresses (eg, Network Service Access Point (NSAP) or personal numbering plan (priva te numbering plans)) can also be supported.   The second part of the collection criteria is to execute on calls that match the filtering criteria. It may specify the measurement to be performed.   The third part of the collection criteria is the service record generated for the call Can specify the measurement or call information to appear in .   The fourth part of the collection criteria is that a partially completed service record is Can be specified to be sent in real time at specific points Noh. Step 2. Capture and filter each SETUP message on the signal channel Matching criteria   The probe ordered to monitor the SETUP message is As noted, this is identified by VPI = 0 and VCI = 5 for unrelated signals And in the case of related signals, identified by VCI = 5 and all VPIs) Captures all SETUP messages from the Hold. A timestamp is also generated upon capture and is stored with the SETUP message. Will be delivered. Step 3. The service level is set for each SETUP message that matches the filtering criteria. Create a code (SR) to include the information from the SETUP message.   Decode and analyze any information element in the SETUP message And the information is used for inclusion in the SR. SETUP message The time stamp of the change is also stored in the SR. Step 4. Identify the virtual circuit associated with the call   SETUP messages or subsequent signaling messages that are part of the same call Conveys information identifying a virtual circuit that will convey communication relating to the call; It is possible to Typically, connection identification information for the SETUP message The element call will identify the VPCI / VCI for the virtual circuit. However, the information shall be carried in a subsequent CALL PROCEEDING message. Is also possible. In this case, the call reference information element (Q .2931 section 4.3) is extracted and the probe has the same calling reference value Capture any CALL PROCEEDING message (PNNI 1.0 section 6.3.1.2) To be ordered. Calls in the opposite direction that may use the same call criteria Care must be taken to distinguish between Can be As a result, the VPCI / VCI for the virtual circuit is called CALL PROCEEDING. It can be distinguished from messages. Step5. Identification of virtual circuits for calls at other monitoring points   Any probe on the link carrying a given SVC will also receive a SETUP message And starts generating the service record for the SVC. This service The problem of duplication of service records is due to the ingress link (or egress) Monitoring system (at step 1) to capture only SETUP messages This can be avoided by configuring the system. However, two measurement points If available, multiple measurements can be taken, which It is particularly useful when mouth points and exit points are monitored.   SETUP messages corresponding to the same SVC must have the same caller and called party number information. Element. The information is sent to a common correlation point, from which point Probes can be commanded to perform two-point measurements in real time . Alternatively, at a later point in time, the calling and called party number information in the service record To combine multiple service records for the same call into one record. You can also stop it. Two-point measurements, such as cell loss, are part of the process. Is calculated. Step 6. Implementing service quality measurements on virtual circuits   Single point measurement: What to do when the virtual circuit carrying the communication is identified An example of a possible single point measurement is a throughput analysis. Transmitted The number of bytes or cells is measured during the call at several time intervals. The throughput distribution (eg, bytes / second) can be calculated. Wide area Distributions indicate significant fluctuations in throughput. This is a constant through Cause problems in any application where puts are required Become.   Other examples of single point measurements include call setup time calculation and TCP / I Measurement of application response time for higher level protocols such as P No.   Two-point measurement: A simple example of two-point measurement is transmission over a virtual circuit. Counting the number of cells at two monitoring points. Those two numbers The difference gives the cell loss. The measurement can be over the entire call, or It can be implemented at intervals during the call.   Another example of a two point measurement is the delay between cells, ie between two measurement points. Measurement of the change in   These quality of service measurements are included in the service record for the call. Quality of service provided by the network. Can also be used to generate overall statistics about. Step 7. Implementation of usage measurement on virtual circuits   Utilization measurements are calculated at a single point. A simple example is Counting of data, cells, or protocol data units. These values are It can be stored as part of the service record of the call. Even higher More complex measurements such as the traffic matrix of the Bell protocol It can also be stored as a separate record for delivery. An important example Generates IP flow records for calls carrying IP traffic It is. This provides other applications with real-time access to IP flow records. Can be used to provide trim. Step 8. RELEASE corresponding to a SETUP message that matches the filtering criteria Continuous monitoring of signal virtual channels for messages   RELEASE and SETUP messages are matched using the calling criteria and the next Used to trigger a step.    − The service detail record for all fields related to the end time and the end reason. Steps to include in the code    − Instructing the probe to stop monitoring RELEASE messages.    -Optionally mark the service detail record as completed and optionally For transferring to an application server or storage server   There should also be a timeout to end monitoring for RELEASE messages. And no RELEASE message is found during the timeout period Mark the service record as completed.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H04M 3/36 H04Q 11/04 L H04Q 11/04 (81) Designated country EP (AT, BE, CH, CY) Carson, Douglas, John Edinburgh, Scotland, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), JP, US EH 12.5 PJ, Rose Balm, Roussel Gardens 6/8 (72) Inventor Reynolds, Alistair, Scott Scotland EH 49.6 Cue, Linlithgow, Mains Road 46 E

Claims (1)

[Claims] 1. A method for monitoring an ISDN link, comprising:       Monitor the subscriber signaling message on the ISDN D channel at the first location To derive the first monitoring data,       An ISDN associated with the ISDN D channel at the first location;   Monitor communication traffic passing through the B channel to derive second monitoring data ,       Correlating the first and second monitoring data,     Monitoring method for the ISDN link. 2. Updates on signaling links in the communication network connected to the ISDN link A third message (eg, SS7 protocol message). Derive visual data,       The third monitoring data is at least one of the first and second monitoring data. Also correlate with one,     2. The method according to claim 1, comprising the steps of: 3. Monitor the subscriber signaling message on the ISDN D channel at the second location; To derive the fourth monitoring data,       An ISDN associated with the ISDN D channel at the second location Monitor communication traffic flowing through the B channel to derive fifth monitoring data;       Correlating the fourth and fifth monitoring data with the first and second monitoring data; Make     2. The method according to claim 1, comprising the steps of: 4. A method for monitoring an ISDN link, comprising:       It monitors the subscriber signaling message on the ISDN D channel to determine the first monitoring data. Data, and       On a signaling link in a communication network connected to said ISDN link Monitor additional signaling messages (eg SS7 protocol messages)     To derive the second monitoring data,       Correlating the first and second monitoring data,     A method for monitoring an ISDN link. 5. A monitoring device for an ISDN link,       It monitors the subscriber signaling message on the ISDN D channel to determine the first monitoring data. A first device at a first location to derive data;       Traffic passing through the ISDN B channel associated with the ISDN D channel. Monitoring the incoming traffic to derive second monitoring data, A second device,       Connected to the first and second devices to receive the first and second monitoring data. To correlate and correlate     A monitoring device for an ISDN link, comprising: 6. A monitoring device for an ISDN link,       It monitors the subscriber signaling message on the ISDN D channel to determine the first monitoring data. First device to derive data       On a signaling link in a communication network connected to said ISDN link Monitor additional signaling messages (eg SS7 protocol messages) A second device that derives monitoring data for       Connected to the first and second devices to receive the first and second monitoring data. To correlate and correlate     A monitoring device for an ISDN link, comprising: 7. Supervision of a communication system having a transmission channel and an associated signaling channel A visual method,       Monitoring a signaling message on the signaling channel at a first location to Derive monitoring data for       A transmission identified by referring to information contained in the first monitoring data; Select a channel,       Communicating communication traffic traversing the selected transmission channel to the first location To monitor and derive second monitoring data,       The above-mentioned selected by referring to the information contained in the second monitoring data To extract further information passing through the     The transmission channel and its associated signal channel, A method for monitoring a communication system having the same. 8. The transmission channel is an ISDN B channel and the signaling channel is an IDN B channel. The method of claim 7, which is an SDND channel. 9. The transmission channel is carried by a telephone transmission link and the signaling channel is 9. The method of claim 7, wherein the signal is carried by a common channel signaling link, such as an SS7 signaling link. The described method. Ten. Said further information includes a dual tone multi-frequency (DTMF) signal; The method according to any one of claims 7 to 9. 11． 2. The method of claim 1, wherein the monitoring at at least one location is passive in nature. The method according to any one of claims 10 to 10. 12． 2. The data correlation is performed to provide a service record. A method according to any one of claims 11 to 11. 13. The service record contains data derived from the ISDN B channel. 13. The method of claim 12, comprising.