1、INTERNATIONAL TELECOMMUNICATION UNION CCITT THE INTERNATIONAL TELEGRAPH AND TELEPHONE CONSULTATIVE COMMITTEE TELEPHONE NETWORK AND ISDN QUALITY OF SERVICE NETWORK MANAGEMENT AND TRAFFIC ENGINEERING E.424 (1 0/92) TEST CALLS Recommendation E.424 CCITT RECflN*Em424 92 486259L 0576476 7T4 FOREWORD The
2、CCITT (the International Telegraph and Telephone Consultative Committee) is a perinanent organ of the Iiiteniational Telecomnunication Union (ITU). CCITT is responsible for studying technical, operating atid tariff questions and issuing Recommendations on them with a view to standardizing telecommun
3、ications on a worldwide basis. The Plenary Assembly of CCITT which meets every four years, establishes the topics for study and approves Recommendations prepared by its Study Groups. The approval of Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid d
4、own in CCITT Resolution No. 2 (Melbourne, 1988). Recommendation E.424 was revised by Study Group II ,and was approved under the Resolution No. 2 procedure on the 30th October 1992. CCIT NOTE In this Recommendation, the expression “Administration” is used for conciseness to indicate both a telecommun
5、ication adtninistration and a recognized private operating agency. l O ITU 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. CCIT
6、T RECMN*E-424 92 4862593 0576477 630 = Recommendation E.424 TEST CALLS (revised 1992) 1 (:eneral Test calls cruried out manually or automatically to assess the functioning of international circuits of connections are of four types: Typt I test ccill A test call conducted between two directly connect
7、ed international centres to verify that the transmission aiid signalling on nn international circuit of a given group are satisfactory. Typa 2 test cri11 A test call conducted between two international centres not directly connected to verify transit operational facilities of an intermediate interna
8、tional centre. Type 3 test cwll A test call from ai international centre to a subscriber type number in the national network of the distant country, generally as a result of a particular kind of fault. Siihsrriber-to-sirhscriber type test cdli) A subscriber-to-subscriber type test call is a test cal
9、l from a test equipment having the characteristics of aii average subscriber line in one national network to a similar equipment in the national network of a distant country. Test calls types I, 2, 3 and subscriber-to-subscriber test calls must not interfere with customer traffic. If, however, test
10、calls coiiuibuting a significant load on a part of a nehvork are to be made, prior advice should be given to the other Adrnitiistratioii(s) concerned. Types 1 aid 2 test calls for preventive maintenance should be conducted during light liad periods. Types 1 and 2 test cds should be conducted as and
11、when required for the investigation and clearance of faults. To aid the effectiveness of test calls type 3, the provision of a 1040 Hz to similar amwering device iii Type 3 test calls should be conducted only after adequate testing has been done by means of type 1 or 2 test udls and after the distan
12、t Administration has made the necess,q check in its national network. Type 3 test calls should he conducted during light load periods. In order to find faults in last-choice equipment, circuit multiplication equipment or in-circuit multiplexing equipment, it may be necessary for tests to be carried
13、out at the time when the traffic load approaches the full capacity of the route under test. The agreement of the distant network analysis point will be necessary before this test is cmied Out. Subscriber-to-subscriber type test cills cati be made by agreement of the network analysis point in the cou
14、ntries ccincenied. Norinally, unless there is a specific agreement between the Administrations concerned, subscriber- 1) verifying that there are no evident faults in the international switching centres involved that would cause the poor Quality of Service or subscriber complaint being investigated;
15、 2) verifying that type 1 or type 2 test crds have been made on the international circuits that might have heeii involved; national networks is recmnmended. to-subscriber type test calls would be considered for fault location after: Krciiiiiiieiiilatiuii M.1235 describes the use of automatic-to-subs
16、criber test calls in more detail. Recommendation E.424 (10/92) 1 CCITT RECMN*E*424 42 4862543 057b478 577 3) verifying that there are no evident faults in the national network from the outgoing exchange to the inteniational centre in the originating country; verifying that there are no evident fault
17、s in the national network in the distant country, froin the international centre to the called exchange. 4) When test calls are undertaken from the inteniational centre to a subscriber number to verify that there are no evident faults in the national network, such calis should be routed through the
18、international centre on the same path as a iionnal incorning international call. Using the test access facilities in the international centre could route calls via a different path thereby masking a fault. When subscriber-to-subscriber type test calls are made, the network analysis point in the two
19、countries i) the expected nature of the fault; ii)- international accounting agreements; iii) the need for making the test calls in the busy hour; iv) the possibility of causing or aggravating congestion at the time the calls are made. The responding equipmeiits used for subscriber-to-subscriber typ
20、e test calls could be those used for should consider such factors as: rnainteriance of the national network. 2 Results of test calls (See Table 1E.424.) 2 Recommendation E.424 (10/92) CCITT RECMNxE.424 92 W 4862591 057b479 403 = TABLE iE.424 Resiilts of test calls Intematinal outgoing exchange: . Ty
21、pe of test call Type la) Type 34 Circuit group: Type 24 semi-automatica) Sub-to-Sba) Semice automatica) Period from to Category 1. Satisfactory tests . 2. Signalling and charging faults . 2.1 Wrong number 2.2 No tone, no answer 2.3 Absence of a backward line signal . 2.4 Other faults . 3. Transmissi
22、on faults . 3.1 Conversation impossible 3.2 Call overamplified or underamplified 3.3 Noise . 3.4 Fading . 3.5 Crosstalk . 4. Congestion . 5. Other faults . Test carried out . Test procedure followed (apparatus used, destination of calls, etc.) Number Subtotal . . . . . . . , . Total , . . . Perccntage Subtotal . . . . . . . Total . . 100 a) Delete whichever is inapplicable. Recommendation E.424 (10192) 3
