Non-intrusive network-based analysis of facsimile transmissions

We claim:

1. An apparatus for monitoring facsimile transmissions as they occur in real time, comprising:

means responsive to some or all communications traffic on selected trunks of a central office switching system for identifying facsimile transmissions on the selected trunks;

means for non-intrusively measuring selected parameters of the identified facsimile transmissions for determining impairments of the facsimile transmissions; and

a user interface for communicating to a user impairments of the facsimile transmissions.

2. The apparatus of claim 1, in which the measuring means comprises a means for measuring protocol signals in the facsimile transmissions.

3. The apparatus of claim 1, in which the measuring means comprises a means for measuring page signals in the facsimile transmissions.

4. The apparatus of claim 2, in which the measuring means further comprises a means for measuring page signals in the facsimile transmissions.

5. The apparatus of claim 1, in which the identifying means further comprises a means for automatically classifying signals appearing on the selected trunks.

6. The apparatus of claim 1, in which the measuring means comprises a means for detecting echo signals on the selected trunks.

7. The apparatus of claim 1, in which the measuring means comprises:

a means for classifying signals on the selected trunks;

a means for measuring transmission impairments related to the signals on the selected trunks;,

a means for detecting echo signals on the selected trunks; and

a means for interpreting protocol messages on the selected trunks.

8. The apparatus of claim 7, further comprising means for integrating signals from the classifying, measuring, detecting, and interpreting means into a data signal representing an event stream in a facsimile transmission.

9. The apparatus of claim 8, further comprising means responsive to the integrating means for analyzing facsimile transmissions appearing on the selected trunks and diagnosing those facsimile transmissions.

10. The apparatus of claim 1, in which the measuring means comprises a means responsive to signaling in the central office switching system for identifying the boundaries of calls on the selected trunks.

11. The apparatus of claim 1, in which the measuring means comprises a means for performing coarse voice band signal classification.

12. The apparatus of claim 1, in which the measuring means comprises:

a means for performing speed classification of signals appearing on the selected trunks; and

a means responsive to the speed signal classification means for identifying at least one characteristic of one or more modems involved in facsimile transmissions on the selected trunks.

13. The apparatus of claim 1, in which the measuring means comprises a means for detecting predetermined tones in facsimile transmissions on the selected trunks.

14. The apparatus of claim 13, in which the tone detecting means detects training tones in the facsimile transmissions.

15. The apparatus of claim 12, further comprising a tone detecting means detects modem training tones in the facsimile transmissions.

16. The apparatus of claim 15, further comprising a modem identifying means is responsive to the speed signal classification means and is responsive to the tone detecting means to identify at least one characteristic of one or more modems involved in the facsimile transmissions on the selected trunks.

17. The apparatus of claim 1, in which the measuring means comprises a means for demodulating protocol signals in facsimile transmissions on the selected trunks.

18. The apparatus of claim 17, in which the demodulating means distinguishes between primary and echo signals related to the protocol signals.

19. The apparatus of claim 12, in which the measuring means comprises a means for demodulating protocol signals in facsimile transmissions on the selected trunks.

20. The apparatus of claim 19, in which the measuring means comprises a means for performing protocol tracking in response to the demodulated protocol signals; and

a means responsive to signals from the modem identification means and the coarse protocol tracking means for producing in-service quality measurement control signals:

21. The apparatus of claim 19, in which the measuring means further comprises a means responsive to page signals in the facsimile transmissions on the selected trunks and to the in-service quality measurement control signals for performing predetermined in-service quality measurements.

22. The apparatus of claim 1, in which the measuring means collects statistics relating to facsimile transmissions on selected trunks of the central office switching system.

23. The apparatus of claim 22, in which the measuring means collects statistics relating to facsimile transmissions directed to a predetermined geographical area.

24. The apparatus of claim 22, in which the measuring means collects statistics relating to facsimile transmissions on predetermined groups of trunks connected to the central office switching system.

25. The apparatus of claim 22, in which the measuring means collects statistics related to the volume of facsimile transmissions on one or more predetermined trunks connected to the central office switching system.

26. The apparatus of claim 25, in which the measuring means collects statistics identifying the volume of predetermined kinds of facsimile transmissions on one or more predetermined trunks connected to the central office switching system.

27. The apparatus of claim 26, in which the measuring means collects statistics relating to the number of facsimile transmissions on one or more predetermined trunks which are completed at certain speeds.

28. The apparatus of claim 22, in which the user interface displays selected statistics related to facsimile transmissions on selected ones of the trunks connected to the central office switching system.

29. The apparatus of claim 1, in which the measuring means comprises a means for measuring trial transmissions in the facsimile transmissions.

30. The apparatus of claim 1, further comprising a tone detecting means for detecting modem training sequences in the facsimile transmissions.

31. The apparatus of claim 29, in which the measuring means further comprises a means responsive to trial transmissions in the facsimile transmissions on the selected trunks and to in-service quality measurement control signals for performing predetermined in-service quality measurements.

32. An apparatus for non-intrusively monitoring facsimile transmissions as they occur in real time, comprising:

a means responsive to communications traffic on selected inbound and outbound trunks of a central office switching system for identifying facsimile transmissions on the selected trunks;

a means for non-intrusively measuring selected parameters of the identified facsimile transmissions for determining selected characteristics of the facsimile transmissions; and

a user interface for communicating to a user any of the selected characteristics of the facsimile transmissions.

33. A public switched telephone network for carrying communications traffic between subscribers to the network, comprising:

at least one network node through which at least a portion of the communications traffic in the network flows;

a means for nonintrusively monitoring facsimile transmissions in the communications traffic through the network node in real time; and

an access control unit connected between the monitoring means and the network node which selectively makes available to the measuring means a predetermined portion of the communications traffic through the network node.

34. The public switched telephone network of claim 33, in which the access control unit connects to the monitoring means data relating to transmissions from a sending facsimile machine to a receiving facsimile machine and data relating to transmissions-from the receiving facsimile machine to the transmitting facsimile machine.

35. The public switched telephone network of claim 34, in which the monitoring means comprises a means for detecting protocol transmissions from the transmitting facsimile machine to the receiving facsimile machine and protocol transmissions from the receiving facsimile machine to the transmitting facsimile machine for ascertaining predetermined characteristics of the facsimile transmissions.

36. The public switched telephone network of claim 35, in which the monitoring means comprises a means responsive to the means for detecting protocol transmissions for making predetermined analog impairment measurements of page signals in the facsimile transmissions.

37. An apparatus for nonintrusively monitoring facsimile transmissions, comprising:

a means for detecting protocol transmissions from a transmitting facsimile machine to a receiving facsimile machine and protocol transmissions from the receiving facsimile machine to the transmitting facsimile machine; and

a means responsive to the detecting means for non-intrusive impairment measurements of page signals in the facsimile transmissions.

38. The apparatus of claim 37, in which the page signals comprise trial transmissions sent by the transmitting facsimile machine to the receiving facsimile machine.

39. A telecommunications network, comprising:

a node for receiving communications traffic comprising facsimile transmissions and non-facsimile transmissions on a plurality of input trunks and for delivering the communications traffic to selected ones of a plurality of output trunks;

a means responsive to the communications traffic for detecting facsimile protocol signals as they occur in real time thereby distinguishing the facsimile transmissions from the non-facsimile transmissions in the communications traffic; and

a means responsive to the detection of facsimile protocol signals for making impairment measurements of the protocol signals and data signals associated with a facsimile transmission.

40. The telecommunications network of claim 39, further comprising:

a means for providing access to selected portions of the communications traffic for identification of facsimile transmissions in those selected portions of the traffic and for measurement of impairments in those facsimile transmissions.

41. The telecommunications network of claim 39, in which the means for making impairment measurements makes impairment measurements on page signals in a facsimile transmission in response to detection of protocol signals associated with that facsimile transmission.

42. An apparatus for monitoring facsimile transmissions as they occur in real time, comprising:

a means responsive to communications traffic flowing through a node of a telecommunications network for identifying facsimile transmissions;

a means for ascertaining a predetermined characteristic of a protocol signal in the facsimile transmission; and

a means responsive to the predetermined characteristic of the protocol signal for determining an impairment of the facsimile transmission.

43. The apparatus of claim 42, in which the means for measuring includes a means for demodulating the protocol signal in the facsimile transmission.

44. The apparatus of claim 43, in which the means for demodulating includes a means for interpreting a message in the protocol signal.

45. The apparatus of claim 43, in which the means for demodulating includes a means for producing an output signal relating to a characteristic of a page signal.

46. The apparatus of claim 43, in which the means for demodulating includes a means for producing an output signal relating to a characteristic of a trial transmission.

47. The apparatus of claim 42, in which the predetermined characteristic is an indication of a speed at which transmitting facsimile equipment sends information to receiving facsimile equipment.

48. The apparatus of claim 47, in which the predetermined characteristic is an indication of a speed at which transmitting facsimile equipment sends page data to receiving facsimile equipment.

49. The apparatus of claim 42, in which the predetermined characteristic is an indication of a characteristic of a modem used by transmitting facsimile equipment to send information to receiving facsimile equipment.

50. The apparatus of claim 49, in which the predetermined characteristic is an indication of a characteristic of a modem used by transmitting facsimile equipment to send page data to receiving facsimile equipment.

Description Submit all comments and votes

TECHNICAL FIELD

This invention relates to facsimile communications. More specifically, this invention relates to characterizing facsimile traffic in a public switched telephone network and to measuring impairments of facsimile transmissions.

BACKGROUND OF THE INVENTION

Communication by facsimile is becoming increasingly important in many areas, particularly, in business communications, because documents may be sent by facsimile from point to point virtually instantaneously. The delays experienced in using other modes of sending documents, such as the postal service, are avoided in transmitting documents by facsimile. The speed with which documents can be sent from one place to another has resulted in greatly increased use of facsimile, which makes it increasingly important that an uninterrupted and reliable level of service be provided on public switched telephone networks so that successful facsimile transmission of an increasing number of documents may be accomplished without significant degrees of impairment. It, therefore, has become increasingly important that the facsimile traffic through a public switched telephone network be accurately characterized. It also has become increasingly important that any impairments of facsimile transmissions be rapidly identified and the source of those impairments be accurately determined so that corrective action may be taken.

Until now, there has been no way to monitor and diagnose, actual facsimile transmissions. There is no available monitoring equipment which obtains convenient switched access to desired portions of the traffic flowing through a public switched telephone network the measure and characterize facsimile transmissions. There is nothing available which analyzes the protocols present in facsimile transmissions and ties that analysis to impairment measurements of the page data in those transmissions. There is no currently available capability of accurately identifying network and customer premises impairments during facsimile transmissions.

Prior techniques of measuring impairments affecting facsimile transmissions involve intrusive techniques which use special test signals which are monitored to ascertain any problems with the transmissions path. This results in test conditions which do not duplicate or simulate the actual conditions experienced during real facsimile transmissions. Thus, the results obtained from these intrusive techniques may not accurately reflect the situation experienced in the course of making a facsimile call. One particularly important deficiency of intrusive testing is that actual customer premises equipment is not involved in making the intrusive tests. Therefore, problems in completing facsimile transmissions caused by the customer premises equipment will not be identified as such with these techniques. The sources of impairment, therefore, may not be accurately identified by intrusive techniques. In addition to the fact that different equipment is connected to the network, the source of those impairments may also not be found due to the artificial nature of intrusive testing. Moreover, the portion of a communications network being tested must be taken out of service to accomplish the testing in accordance with prior techniques, and thus this part of the network will be unavailable for normal use.

Prior devices which measure communications signals are not able to adequately characterize a facsimile transmission non-intrusively as the transmission takes place. Moreover, if it were attempted to use this equipment for characterizing facsimile transmissions, the equipment only would be able to obtain dedicated access to a single facsimile apparatus at a time. Thus, identification of all the possible problems in a large communications network, such as a public switched telephone network, are impossible or impractical. There has been no equipment available which is capable of conveniently measuring in any meaningful fashion facsimile traffic in a public switched telephone network so that sources of impairment to those transmissions could be effectively identified and rapid and effective corrective action could be taken.

Accordingly, there is a significant and long-standing unsatisfied need for equipment which can properly analyze actual facsimile transmissions in a public switched network.

SUMMARY OF THE INVENTION

The need identified above is met by an apparatus which non-intrusively monitors real time facsimile transmissions as they are occurring in a network. The apparatus can obtain convenient access to any part or all of the communication traffic flowing through a network node. It may characterize the amount and kind of facsimile calls being made and it may measure certain characteristics of those calls. The apparatus may detect certain characteristics of protocol signals in facsimile transmissions and may activate certain analog impairment measurements in response to the characteristics of the protocol signals.

One example of such a non-intrusive monitor of facsimile transmissions comprises a means responsive to selected inbound and outbound trunks of a central office switching system which identifies the presence of facsimile transmissions on those selected trunks. Selected parameters of the identified facsimile transmissions are determined and a user interface communicates to a user selected characteristics of, and any impairments found in, the measured facsimile transmissions. The non-intrusive nature of the facsimile transmission measurements permits the network to remain in service during the measurement procedures so that revenue is not lost during the measurement procedure. Measurement of actual facsimile transmissions experiencing impairments gives an accurate picture of what is going on in the course of those transmissions so that the identity and the source of impairments may be more accurately determined and so that prompt and efficient corrective action may be taken.

In another example of the invention, a user of a facsimile analyzer in accordance with this invention may select for analysis predetermined portions of the communications traffic flowing through a network node. The facsimile apparatus obtains non-intrusive access to the selected portion of the communications traffic for a predetermined time. Facsimile transmissions are identified and measurements are taken and recorded for each such transmission. Problems with each facsimile transmission are diagnosed. Statistical information about facsimile transmissions in the observed part of the communications traffic is derived. The data is collected and the diagnoses produced are stored in one or more data bases. The user can call up selected portions of this information on a user interface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a public switched telephone network in accordance with this invention containing an apparatus for characterizing and measuring impairments of facsimile transmissions carded by the network.

FIG. 2 is a detailed schematic diagram showing an example of a connection between a facsimile measurement apparatus and a node in a public switched telephone network like the one shown in FIG. 1.

FIG. 3 illustrates a full duplex monitoring function carded out by a facsimile measurement apparatus in accordance with this invention.

FIGS. 4 to 6 illustrate the steps carried out by a facsimile measurement apparatus in accordance with this invention to accomplish a full duplex directed test access function.

FIG. 7 illustrates the main circuit elements in a facsimile analysis apparatus in accordance with this invention.

FIG. 7a illustrates the main signal components flowing from a transmitter to a receiver during an example of a typical G3 facsimile call.

FIG. 8 is a more detailed schematic diagram of some of the circuit elements shown in FIG. 7.

FIG. 9 is a more detailed schematic diagram of the circuitry used to implement the in-service quality measurement apparatus shown in FIG. 8.

FIG. 10 is a more detailed schematic diagram of the circuitry in the demodulator shown in FIG. 9.

FIG. 11 is a more detailed schematic diagram of the circuitry in the constellation analyzer shown in FIG. 9.

FIGS. 12 to 12c illustrate examples of thresholds used by the impulse noise measurement circuit shown in FIG. 11.

FIG. 13 is a flow chart specifying circuitry in the computer shown in FIG. 2 for accomplishing diagnosis of facsimile transmissions received by facsimile analysis equipment in accordance with this invention.

FIG. 14 is a state diagram illustrating an example of the operation of the state machine of FIG. 13 for a typical G3 type facsimile transmission without an error correction mode.

FIG. 15 is a block diagram illustrating the database architecture in the computer of FIG. 2.

FIG. 16 illustrates an example of a menu of options available to a user of a facsimile measurement apparatus in accordance with this invention.

FIG. 17 is an example of a country list available to a user of a facsimile measurement apparatus in accordance this invention.

FIG. 18 is an example of a trunk list available to a user of a facsimile measurement apparatus in accordance this invention.

FIG. 19 is an example of a session list available to a user of a facsimile measurement apparatus in accordance this invention.

FIG. 20 is an example of a session summary produced in accordance with one example of this invention.

FIG. 21 is an example of a call list produced in accordance with one example of this invention.

FIG. 22 is a call summary produced in accordance with one example of this invention.

FIG. 23 is an events list produced in accordance with one example of this invention.

FIG. 24 is an example of analog impairment measurements displayed for one of the events in FIG. 23.

FIG. 25 is an example of raw data taken for one of the events shown in FIG. 23.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram showing an example of a public switched telephone network containing a facsimile analyzer for purposes of monitoring facsimile calls in the network. FIG. 1 also shows illustrative transmitting facsimile equipment, receiving facsimile equipment, and the lines, trunks, and nodes in the network used to complete a facsimile call between the transmitting facsimile equipment and the receiving facsimile equipment. In FIG. 1, a transmitting facsimile equipment 10, which may be a so-called Group 3 facsimile machine, is connected to a public switch telephone network via a subscriber line 12, which may be a pair of wires.

The subscriber line 12 is connected so as to form a subscriber's loop between the transmitting facsimile equipment 10 and an end office 14 of the public switched network. In the U.S., the end office 14 may be a local exchange office of one of the Regional Bell Operating Companies (RBOC's) and the like. The end office 14 may be connected by a trunk 15 to a toll switch 16 located in one of the central offices in a domestic or international inter-exchange long distance network 17. The inter-exchange network 17 also contains other toll switches and trunks which are used to connect other calling parties not shown in FIG. 1 to other called parties also not shown in FIG. 1. The long distance network may be one of those provided by a long distance carrier such as AT&T. Only the toll switches and trunks connecting the transmitting facsimile equipment 10 with the receiving facsimile equipment 11 are shown in FIG. 1. In addition to those items already described, the connection between the transmitting facsimile equipment 10 and the receiving facsimile equipment 1 t further comprises a trunk 18 connecting a toll switch 16 to a toll switch 20, a trunk 22 connecting toll switch 20 to a toll switch 24, a trunk 26 connecting the toll switch 24 to another end office 28 which is connected to the receiving facsimile equipment 11 via another subscriber line 30.

The public switched network of FIG. 1 has a system for identifying facsimile transmissions in selected portions of the total communications traffic on the network and for performing certain measurements and analysis on the identified facsimile transmissions which are useful in identifying the amount and kind of facsimile transmissions flowing in the network and the extent to which successful facsimile service is being accomplished on the network. These measurements are made non-intrusively in real time as the facsimile transmissions are occurring. These measurements are useful in diagnosing the causes of difficulties in successfully completing facsimile transmissions through the network and in characterizing in some meaningful way the amount and kind of facsimile transmissions through the network.

In this regard, the network of FIG. 1 contains one or more facsimile measurement systems connected to components of the network through which the measurement system can obtain non-intrusive access to some or all of the communications traffic in the network.

One of those facsimile measurement systems 32 is shown in FIG. 1. That measurement system 32 is connected to one of the toll switches 20 so that selected portions or all of the communications traffic through the toll switch 20 can be observed in a non-intrusive manner. Facsimile calls can thereby be identified, certain characteristics of those facsimile calls can be measured, and the nature and source of any impairments of the calls can be found and diagnosed. Although FIG. 1 explicitly shows only one measurement system 32 connected to one switch in the public switched network, any number of measurement systems may be used anywhere else in the network where access to desired traffic through a selected part of the network may be easily gained. As is apparent from the description below, individual customer problems can be detected and addressed and aggregate fax service usage and quality in the network may be determined.

FIG. 2 shows a more detailed example of an architecture which contains a facsimile measurement system 32 connected to a portion of a public switched telephone network so as to gain access to some or all of the communications traffic in the network. The architecture of FIG. 2 comprises a measurement system 32 for analyzing facsimile traffic on a selected portion of a public switched telephone network. The measurement system 32 also comprises a service signal processor 34 which analyzes one or more calls. Such analysis includes identification of the presence of facsimile calls and the boundaries of those calls, performance of signal classification, measurement of certain signal characteristics, and presentation of the results to a diagnostic computer 35 and a user interface 36. The computer 35 receives data from the service signal processor 34 on a suitable link 38, which may be, for example, a X.25 9.6 kb/sec data link. The data received from processor 34 is stored in one or more data bases contained within the computer. The computer 35 contains software which performs diagnostic analysis of the data from processor 34 which may help to identify the potential sources of any abnormalities in the characteristics of facsimile calls measured by processor 34. Any desired part of the data collected by the processor 34 and stored in the data base in the computer 35 may be called up and displayed by a user through the user interface 36. The user interface 36 operates in response to appropriate commands generated by a user via a peripheral device such as a mouse or keyboard connected to the computer 35.

An access control unit 40 is linked to a network node 42 controlling the flow of communications traffic through the public switched telephone network of FIG. 1. The network node may be any of a variety of equipment through which communications traffic flows. For example, the network node 42 may be a central office switching system which controls the connection between a variety of inbound and outbound trunks of the public switched telephone network. By way of example, such a switching system may be an AT&T 4ESS.TM. or 5ESS.RTM. switching system. The network node 42 may also be similar switching systems from other manufacturers. One other suitable example of a network node 42 in FIG. 2 is a digital cross-connect system such as a digital access cross-connect system (DACS) made by AT&T.

The access control unit 40 may be any circuit which can access a selected portion of the communications traffic flowing through the network node 42. For example, the access control unit 40 may be the digital test unit (DTU) in an AT&T remote measuring system (RMS). The access control unit 40 is responsive to a command from the computer 35 generated in response to a request by a user of the facsimile measurement system 32 for information about a specific portion of the communications traffic flowing through the network node 42. The access control unit 40 makes a suitable request, via an input/output I/O link 44, for the network node 42 to map one or more DS0 signals flowing through it, including any signalling information corresponding to the phone calls represented by the selected DS0 signals, to a DS1 link 46 connecting the access control unit 40 with the network node 42. As those skilled in the art are aware, one phone call comprises a pair of DS0's, a transmit DS0 and a receive DS0, which may be mapped to adjacent DS0 time slots on the DS1 signal in the line 46. The techniques of mapping signals from a network node to a predetermined place in a bit stream like the one between the network node 42 and access control unit 40, by copying data relating to a specific DS0 stored from time-to-time in specific locations in the network node onto the bit stream on line 46, are well-known to those skilled in the art and, therefore, are not described further. Any such mapping technique may be used to carry out this invention. The selected DS0 signals mapped onto the bit stream on line 46 are directed to one input of the service signal processor 34 via the operation a digital bridging repeater 48 connecting the line 46 to the input of the service signal processor 34. The service signal processor 34 then identifies call boundaries from signalling information associated with the DS0 signal, identifies the nature of any phone calls on the selected DS0, and makes certain measurements and observations regarding any facsimile transmissions associated with that DS0 signal. Signalling information, which is used by the service signal processor 34 to identify call boundaries, may be communicated to the service signal processor 34 by setting the state of one or more predetermined bits in the stream of bits flowing between the network node 42 and the access control unit 40. For example, two state robbed A-bit signals may be used. Alternatively, the call signalling may be communicated to the service signal processor 34 via a communication channel which is separate from the DS1 link 46.

The apparatus of FIG. 2 may be operated in two separate modes. The first mode is a full duplex monitoring mode which enables the service signal processor 34 to monitor both directions of one or more switched connections through a network node 42 such as a 4ESS.RTM. type switch. The second mode is a directed test access mode in which there is the establishment of a full duplex monitor connection directed to a specific switched connection originated by a customer experiencing problems in completing a specific facsimile transmission.

The full duplex monitor capability of the apparatus of FIG. 2 is illustrated in more detail in FIG. 3. As shown in FIG. 3, the access control unit 40 causes the network node 42 to map a desired portion of the communications traffic through the node onto the link 46 between the access control unit 40 and the network node 42. In one example of the invention, the access control unit 40 sends a command over the link 44 to the network node 42 which causes the network node 42 to map a specific DS0 signal flowing through the network node to a preselected slot on a DS1 receive frame carried by the link 46. The selected DS0 signal is mapped from a trunk 50, as indicated by arrow 52, to a slot designated primary TAT X (standing for test access trunk X) in the DS1 receive frame on the link 46. A corresponding DS0 on a connected trunk 54 is mapped, as indicated by line 56, to an adjacent slot in the DS1 receive frame designated associated TAT X+1 (standing for test access trunk X+1) in FIG. 3. The DS0 on trunk 54 is the DS0 which is the return associated with the selected DS0 on trunk 50 by the switch fabric of the network node 42. Monitoring both the DS0 associated with the send leg of trunk 50 and the corresponding DS0 associated with the receive leg of trunk 54 thus provides a full duplex monitor for a period of time specified by the user. A bridging repeater 48 provides the signals in the primary and associated TAT slots to the service signal processor 34 for measurement and analysis.

In one embodiment of the invention, the monitoring function is established by a suitable user command directed to the computer 35 which then causes the access control unit 40 to provide the service signal processor 34 access to a desired portion of the traffic through the network node 42 for an indefinite period of time until the monitoring operation is terminated by an abort command entered by the user into the computer 35. In another embodiment, the computer 35 may be programmed to provide a monitoring operation for a predetermined amount of time with automatic discontinuance of the monitoring operation after the expiration of the predetermined amount of time.

Individual problems experienced by a network customer in completing facsimile transmissions can be assessed by facsimile analysis equipment in accordance with this invention by operating that equipment in the directed test access mode mentioned above. In this mode, a customer experiencing difficulty in completing a facsimile transmission first calls a special number, such as a special 800 number, which establishes a dialog with network personnel responsible for operating facsimile measuring equipment in the telephone network. The customer notifies these personnel of the nature of the problem, the identity of the destination telephone number to which facsimile transmission is being attempted, and the identity of the telephone number from which the facsimile transmissio