ITU-T F 70-1993 EVALUATING THE QUALITY OF THE INTERNATIONAL TELEX SERVICE《视听 多媒体业务的框架建议》.pdf

1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 b) the retention of the established connection;c) the satisfactory transmission quality;d) the integrity of billing.1.3 Where possible, the critical areas of service performance should be measured in a manner that provides bothorigin and destination Admin

2、istrations with comparable data. For example, arrangements to ensure concurrency of theperiods of observation by the two Administrations involved in each given relation is of great importance. Thesemeasurement should, if possible, show the performance as perceived in the originating network and in t

3、he destinationnetwork.1.4 Where a subscriber number is found to be “hard to reach” (HTR), then, if possible, this number should beseparately identified to allow the origin and destination Administrations mutually to analyze the cause of the problem.2 Method of measuring quality of service2.1 Adminis

4、trations should draw up a programme for telex observations designed to evaluate the quality of theservice given to subscribers in their automatic and semi-automatic international services.2.2 Where Administrations have equipment that automatically records details of calls, this information may be us

5、edto compile details of network performance.2.3 In order to provide compatible data between the origin and destination networks, where possible,Administrations should measure the perceived performance in the origin network (e.g., at the entry point to theinternational gateway exchange if applicable)

6、 in addition to the performance at the international interface lookingtowards the destination network.3 Analysis of results3.1 Administrations should exchange data on a bilaterally agreed basis, commensurate with their operationalrequirements and, in principle, at least once every six months.3.2 The

7、 results may then be analyzed as shown below (see also Table 1/F.70):a) Check effective rate to the destination compared with the average to all destinations.b) Check the current rate versus the performance as measured in the past.c) Check the performance with results obtained by other Administratio

8、ns to the same destination.d) If the performance has suddenly degraded, perform a detailed analysis where possible, monitor circuitgroup performance and analyze the performance on a destination code basis. The degradation on a circuitgroup could be caused by a faulty circuit which, when seized, fail

9、s to successfully switch a call.3.3 Administrations should investigate any HTR report (greater than 50 unsuccessful attempts to one numberwithin a day could be defined as being HTR).2 Fascicle II.4 - Rec. F.703.3.1 Where national regulatory arrangements allow, Administrations should check that autom

10、atic terminalequipment complies with Recommendation U.40. Where poor terminal operating procedures exist, customers should bereferred to the guidelines annexed to Recommendation F.60.3.3.2 The destination Administration should proceed as follows:3.3.2.1 OCC : the called subscriber should be advised

11、that his telex machine is very busy and that extra machines(or terminations) may be necessary.3.3.2.2 DER : is this still a working service? If not, the service signal should be changed to NP or NCH. If theservice is still working, the customer should be asked if the machine is being disabled, e.g.,

12、 by switching off the power.If a computer interface is being used, is the telex machine being correctly switched in when the computer is taken off-line?3.3.2.3 NP/NCH : consult the origin Administration and ask it to take the matter up with the calling subscriber.3.3.2.4 Answerback failure:a) Where

13、answerback failure occurs, the reasons should be investigated by the destination Administration.b) Where a calling automatic terminal fails to interpret the answerback correctly, the reasons should beinvestigated by the origin Administration.3.4 Where possible, Administrations should also investigat

14、e and report as necessary when frequent cases ofclearing from the destination network occurs after charging commences, since a likely cause in such cases is atransmission fault during the text transmission.3.5 Regular discussion should take place with other Administrations, on a bilateral basis, wit

15、h a view towardsimproving the mutual network performance.4 Explanation of terms used in Table 1/F.704.1 Effective callAn effective call is defined as a call for which a charge was made or that was successfully completed to aservice position. Where possible, measurements should be corrected to take a

16、ccount of any calls for which the chargehas been adjusted.4.2 Ineffective callAny calls or call attempts that did not result in an effective call.4.3 Chargeable timeDuration between the call-connected signal and recognition of the clearing of a call, less 5 to 7 seconds (seeRecommendation F.61).4.4

17、Call set-up timeThe time between circuit seizure and the receipt of a call-connected or service signal. This time will not be thesame on the national and the international sides of the exchange.4.5 PTS failureThe proceed-to-select signal has not been received within a nominated period after a call s

18、ignal has been sent tothe next exchange.4.6 Service signals(ABS, DER, NA, NC, NCH, NP, OCC) are defined in Recommendation F.60, 4.1.Fascicle II.4 - Rec. F.70 3TABLE 1/F.70International telex service observationsADMINISTRATION:TRAFFIC OUTGOING FROM: TOPERIOD OF OBSERVATION: UTC TO UTCROUTE BUSY HOUR:

19、 UTC TO UTCNumber of observations Point of observationNational sideInternational side(Includes retries)National side International sideAverage thisdestinationAverage alldestinationsAverage thisdestinationAverage alldestinationsPercentageEffective calls Chargeable time (min. sec.)Call setup time (min

20、. sec.)Ineffective calls PercentageCall setup time (min. sec.)Analysis of ineffective calls (Expressed as percentage)PTS FailureOCC Signal receivedDER Signal receivedNP Signal receivedABS Signal receivedNC Signal from distant networkOutgoing circuitNA Signal receivedselectedNCH Signal receivedOther

21、service signalsNo answer back after call connectClear by caller before call connectNo call connect (time out)Cut off during call setupWrong number reachedOthers (specify)No outgoing circuitIncomplete numberselectedClearing before complete numberLack of outgoing circuitsTHE FOLLOWING NUMBERS WERE IDENTIFIED AS HARD TO REACH TELEX SUBSCRIBERS:SERVICE SIGNAL RECEIVED ON INTERNATIONAL SIDECalled number OCC DER ABS NS Others (specify)Note An explanation of terms is given in 4.