1、ITU-T RECMN*E=422 96 = 48b259L 0627334 702 INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU E.422 (02/96) TELEPHONE NETWORK AND ISDN QUALITY OF SERVICE, NETWORK MANAGEMENT AND TRAFFIC ENGINEERING OBSERVATIONS ON INTERNATIONAL OUTGOING TELEPHONE CALLS FOR QU
2、ALITY OF SERVICE ITU-T Recommendation E.422 (Previously “CCIlT Recommendation“) FOREWORD The T-T (Telecommunication Standardization Sector) is a permanent organ of the International Telecommunication Union (ITU). The ITU-T is responsible for studying technical, operating and tariff questions and iss
3、uing Recommen- dations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, establishes the topics for study by the T-T Study Groups which, in their turn, produce Recommendations on
4、these topics. The approval of Recommendations by the Members of the ITU-T is covered by the procedure laid down in WTSC Resolution No. 1 (Helsinki, March 1-12, 1993). -T Recommendation E.422 was revised by IT-T Study Group 2 (1993-1996) and was approved under the WTSC Resolution No. 1 procedure on t
5、he 19th of February 1996. NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. O ITU 1996 All rights reserved. No part of this publication may be reproduced or utilized in any form
6、or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the IT. 6 7 8 9 10 11 12 13 ITU-T RECMN*E.422 7b 48b257L Ob117336 584 CONTENTS Objectives concerning Tables 1 to 4/E.422 Manual or semi-automatic observations (Table 1E.422) Comments c
7、oncerning the use of Table 1E.422 How to fill in Table 1E.422 . Automatic observations for CCITT Signalling Systems other than Signalling System No . 7 (Table 2iE.422) Comments concerning the use of Table 2fE.422 How to fill in Table 2fE.422 . Comments concerning the use of Table 3R.422 How to fill
8、in Table 3E.422 . Comments concerning the use of Table 4/E.422 How to fill in Table 4R.422 . Automatic observation for Signalling System No . 7 - Tup (Table 3E.422) Automatic observations for CCITT Signalling System No . 7 - ISUP (Table 4E.422) . Page 1 1 2 2 5 5 7 8 8 8 10 10 10 Recommendation E.42
9、2 (OY96) 1 ITU-T RECMN*E*422 96 = 4862591 0637337 410 SUMMARY This Recommendation describes service observation in the international service in order to assess the quality of service obtained by the calling subscriber. It is essential to have factual or objective recording of observations (i.e. succ
10、essful and unsuccessful calls), and to present them in the form of tables. The purpose of the revisions to this Recommendation are to include common channel Signalling System No. 7 features, to augment the QOS observations for Signalling Systems No. 5. No. 6 and R2 already present. 11 Recommendation
11、 E.422 (OZ96) ITU-T RECMN*E.422 96 W 4862571 Ob37338 357 Recommendation E.422 OBSERVATIONS ON INTERNATIONAL OUTGOING TELEPHONE CALLS FOR QUALITY OF SERVICE (revised in 1996) 1 Objectives concerning Tables 1 to 4m.422 1.1 The purpose of service observation in the international service is to assess th
12、e quality of service obtained by the calling subscriber. Consequentiy, it is essential to have factual or objective recording of observations (i.e. successful and unsuccessful calls), and to present them in the form of a table (see Table 1 for manual or semi-automatic observations, and Tables 2,3 an
13、d 4 for automatic observations). 1.2 The modem trend is to carry out automatic measurements for the following reasons: - - continuous observation is possible; - - human error is eliminated; - - conversational privacy is ensured; - operating costs are minimized (staff reduction); it is possible to ta
14、ke a larger sample; automatic processing of data is facilitated; the time at which observations are made can be recorded. The increasing deployment of out-of-band signalling system as Signalling System No. 7 Tup and ISP greatly enhance the value of these observations permitting a comprehensive analy
15、sis of traffk quality of service. However, manual observations may prove useful in monitoring transmission impairments such as noise, echo, clipping and distortion. 1.3 is recommended that, for automatic observation: Due to the different capabilities and limitations of each signalling protocol used
16、in the international network, it - - - Table 2 be used for CCITT Signalling Systems other than Signalling System No. 7. Table 3 be used for CCIT Signalling System No. 7 - Tup (Telephone User Part). Table 4 be used for CCIT Signalling System No. 7 - ISW (ISDN User Part). 2 Manual or semi-automatic ob
17、servations (Table UE.422) 2.1 from the simple to the sophisticated. Table 1 should be capable of being completed through the use of a wide range of observation facilities, i.e. 2.2 Specialized training of observers should be kept to a minimum. 2.3 2.4 The table should be self-explanatory so that ref
18、erence to detailed how-to-complete instructions is unnecessary. The major categories should be selected such that: - - 2.5 To permit the orderly collection of data for human factors studies to identi sources of difficulty in customer use of the international (automatic) telephone service, Recommenda
19、tion E.427 contains an additional table to Table 1m.422. they identify the major factors adversely affecting the quality of service; they are suitable for the centralized processing of observation results. Recommendation E.422 (02/96) 1 ITU-T RECMN*E.422 96 = 4862571 Ob17337 293 . TABLE 1E.422 A3 Un
20、successfui calls: Posihve indication of congestion, including subscriber busy, from beyond the outgoing international exchange. Visual signai, tone or recorded announcement 3.1 Subscriber busylcongestion indicated by visual signai 3.2 Subscriber busylcongestion indicated by busylcongestion tone 3.3
21、Congestion indicated by a recorded announcement A4 Unsuccessful calls: Other visual signais, tones or recorded announcements, not positively identified as Category 3 or 8 4.1 Visual signal received 4.2 Tone received 4.3 Recorded announcement received A5 Unsuccessful cais for other technical reasons
22、5.1 Wrong number obtained 5.2 Abandoned due to very poor speech transmission 5.3 No tone, no answer after waiting . seconds 5.4 Reception of answer signal when the called party does not reply 5.5 Other failures of a technical kind A6 Unsuccessful cab due to incorrect handling by the calling party 6.
23、1 Wrong number dialled 6.2 Incomplete number 6.3 Call prematurely abandoned before receipt of signal, tone or announcement (within less than . seconds) 6.4 Call prematurely abandoned after receipt of ring tone (within les than 30 seconds) 6.5 Other failures due to incorrect handling Observations of
24、international outgoing telephone caiis for quality of service Country of origin Point of access: . Outgoing international exchange . National side . Group of circuits Link circuits Service Period: from to . Outgoing side automatica) i semi-automatica) Time of observations Category Al Cais successful
25、ly put through (see Note 1) A2 Ring tone received but no answer Number Subtotal . . . . . . . . . . . . . . . . Total . . . . . . Percentage Subtotal Total . . . . . . . . . . . a . . . . . . . . . . 2 Recommendation E.422 (02/96) ITU-T RECMN*E.422 b 48b2593 Ob37340 TO5 TABLE 1E.422 (Concluded) Obse
26、rvations of international outgoing telephone caiis for quality of service I Category I A7 Total caUs monitored (Category 1-6) A8 Unsuccessful calls: Positive indication of failure from outgoing international exchange 8.1 Congestion on outgoing international circuits 8.2 All other indications A9 Succ
27、essful calls with defects. These caih are included in Category 1 9.1 Non-reception of answer signal on chargeable calls 9.2 Call with impaired intelligibility but not abandoned Number Subtotal . . . . . Total . . . Percentage Subtotal + 9.3 Other calls with defects but not abandoned Delete whatever
28、is inapplicable. NOTES 1 A successful call is one that reaches the wanted number and allows conversation to proceed. All successful calls are entered in Category 1. However, a successful call may or may not have noticeable defects. Successful calls with noticeable defects should also be entered in C
29、ategory 9. 2 category only, namely the most appropriate one from 1 to 6. 3 Categories 4.1,4.2 and 4.3. With the exception noted above for Categories 1 and 9, the results of one call observation should be entered under one Administrations should periodically exchange necessary information to interpre
30、t the observation data recorded under 3 Comments concerning the use of Table UE.422 3.1 Table 1 summarizes observations made on outgoing automatic andior semi-automatic traffic, on a country of origin to a country of destination basis. A separate form should be used for each country of destination,
31、and if required, for each group of circuits to which traffic to a country of destination has access at the outgoing international exchange (or exchanges). It is not necessary to make observations on both automatic and semi-automatic services. An Administration may select the service to be observed,
32、provided that the service is the majority of the traffk to the country of destination. 3.2 3.3 several faults on one call, the most significant cause of failure should be entered. 3.4 For an explanation of the point of access, see 4.1E.421. The result of each call observed should be entered only und
33、er the most appropriate category. In the case of In completing Table 1 reference should be made to the following explanations. 4 How to fill in Table UE.422 Category Al - To ensure objective recording and to avoid producing a biased sample resulting from the exclusion of calls which require subjecti
34、ve assessment, the successful call is defined as a call that reaches the wanted number and allows conversation to proceed. All non-abandoned calls are entered into Category 1 and of these calls those which are subjectively adjudged to be defective are also entered into Category 9. Thus it is require
35、d of the observer to make WO entries for successful calls with noticeable defects. Recommendation E.422 (OW%) 3 Enter in Category 1 then, calls successfully put through. This includes answered calls for which a clearback signai is received after some words have been spoken, without knowing for what
36、reason the call is abandoned. If it is observed that the caller has dialled a wrong number, the call will be entered under 6.1. Category 1 will also include calls put through correctly to operator positions, information services, or to machines replying in place of the subscriber or to their equival
37、ents. Category A2 - Enter in this category calls on which ring tone was heard but the subscriber did not answer before the attempt was abandoned, the caller having waited at least 30 seconds after commencement of ring tone before clearing forward. (See Category 6.4 if the call was abandoned less tha
38、n 30 seconds after ring tone commenced.) Category A3 - Enter in this category all unsuccessful calls in which a positive indication of subscriber busy or congestion beyond the outgoing international exchange had been encountered, either by visual signal, tone or recorded announcement. Congestion enc
39、ountered on common control equipment should be entered in this category as well (e.g. no “proceed-to-send” signal). Where a positive indication of these conditions has not been received, enter in Category 4. Categories 3.1.3.2 and 3.3 are entered for the specific indication received. When more than
40、one indication is received, e.g. visual signal and audible tone, only one entry should be made. In this case, the preferre order of entry should be tone, announcement, visual signal. Category A4 - Enter in this category all other indications on unsuccessful calls whether by visual signai, tone or re
41、corded announcement that cannot be positively identified and entered in Category 3 or 8. Categories 4.1,4.2 and 4.3 are entered for the specific indication received. When more than one indication is received, e.g. visual signal and audible tone, only one entry should be made. In this case, the prefe
42、rred order of entry should be tone, announcement, visual signal. Category A5 - Enter in this category those calls which fail for technical reasons not included in Categories 3,4 and 8. Category 5 subdivides as follows: - - Category 5.1 - Calls on which the wrong number was obtained, although the cal
43、ler dialled correctly. Category 5.2 - Calls abandoned by the caller because of very poor speech transmission, although the answer signal was received. (See Category 9.2 if speech transmission is poor but the cai1 is not abandoned.) In some countries observers may be required to cease listening immed
44、iately after conversation is established, thus reducing the number of calls that would be reported in this category. Category 5.3 - Calls on which the dialling information was correctly and completely sent, but the caller received no signal, tone or announcement before abandoning the call, having wa
45、ited for at least the specified period before clearing forward. The value of this time period left open under this category should be filled in by the Administrations of the originating country according to its experience in this matter. The prescribed value may differ depending on the international
46、 destination. It is, however, recommended to limit the number of such different quoted periods to a maximum of three values (e.g. 10, 20 or 30 seconds or any other value considered pertinent by the Administrations concerned). - - Category 5.4 - Calls on which an answer signai was received, although
47、the called subscriber did not answer. - Category 5.5 - Call failures due to technical reasons which are unable to be entered in Categories 5.1 to 5.4. These should be very few, if any, and this category is provided in case they do arise. All possible information about these failures should be suppli
48、ed as an attachment to the summary of the table. This category includes calls abandoned due to reception of a clear-back signal while connecting with the extension number (PBX), Category A6 - Enter in this category all unsuccessful calls which have failed due to incorrect handling by the caller (sub
49、scriber or operator). Category 6 subdivides as follows: Category 6.i - Calls on which it was determined that the number which should have been dialled was different from the number actually dialled. Category 6.2 - Calls on which it was determined that the number dialled had insufficient digits to be successful. - - 4 Recommendation E.422 (02/96) ITU-T RECMN*E.Y22 76 4862573 Ob37342 BBB = - Category 6.3 - Calls on which the digitai information was correctly and completely sent, but the caller abandoned the call without receiving any signal, tone or announcement, and with
