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.426 (1 0/92) GENERAL GUIDE TO THE PERCENTAGE OF EFFECTIVE ATTEMPTS WHICH SHOULD BE OBSERVED FOR INT
2、ERNATIONAL TELEPHONE CALLS Recommendation E.426 CCITT RECMN*E-426 92 4862593 0576487 58T = FOREWORD The CCITT (the Interaational Telegraph aiid Telephone Consultative Committee) is a permanent organ of the International Teleconmunication Union (ITU). CCITT is responsible for studying technical, oper
3、ating aid tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The Plenary Assembly of CCITT which meets every four years, establishes the topics for study arid approves Recommendations prepared by its Study Groups. The approvai o
4、f Recommendations by the members of CCITT between Plenary Assemblies is covered by the procedure laid down in CCITT Resolution No. 2 (Melbourne, 1988). Recoininendation E.426 was revised by Study Group II and wr?s approved under the Resolution No. 2 procedure on the 30th October 1992. CCITT NOTE In
5、this Recommendation, the expression “Adinitiistration” is used for conciseness to indicate both a telecommunication administration and a recognized private operating agency. O ITU 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any meais, electro
6、nic or tnechmical, including photocopying and microfilm, without permission in writing from the ITU. - - _ -_ - CCITT RECflN*E-426 72 4862591 0576488 416 i Recornmendation E426 GENERAL GUIDE TO THE PERCENTAGE OF EFFECTIVE ATTEMPTS WHICH SHOULD BE OBSERVED FOR INTERNATIONAL TELEPHONE CALLS (revised 1
7、992) 1 (:eneral considerations 1.1 The success of call attempts is fundamental to an automatic international telephone service of high quality. 1.2 The periodic observation of completion ratio) and the categorization of failures to destination countries together with the exchange of such information
8、 between countries are valuable to establish and/or maintain a high service qudity. 1.3 The call completion ratio of the national network of a given country, as manifested through its international switching centre(s), affects the efficiency of operation of all countries routing traffic to that coun
9、try. 1.4 Call completion ratio information can be provided either internally in a stored program controlled (SPC) international switching centre or externally at the level of the outgoing international circuits in any international switching centre in which access to the circuits is provided for the
10、 purpose of establishing the disposition of call attempts. 1.5 The availability, flexibility and capacity of minicomputers provides an economically attractive method of obtaining call completion ratio information with extreme accuracy. This includes the observation of tones when suitable interfaces
11、with the minicomputer are provided. 2 A guide to the proportion of effective call attempts 2.1 A general guide for the expected percentage of effective call attempts during the mean busy hour for the specific country (or area code) route, its two adjacent hours, and the whole day, as observed at the
12、 originating international switching exchange is indicated below. An effective ca1 attempt is defined, for this purpose, as one for which an answer is received at the originating international exchange. Faults caused by the originating international exchange shall be excluded to the extent feasible.
13、 All attempts which succeed in seizing an international circuit shall be included in the results: a) b) c) 2.2 When an originating country notes a downward change in the level of effective call attempts towards any destination, the originating, destination or transit Administrations should initiate
14、investigations to determine and alleviate the underlying causes (e.g. network provisioning, subscriber behaviour). The objective of this action is to avoid degrad?tion in the level of effective call attempts. low level of effective call attempts: less than 30%; medium level of effective call attempts: 30% to 60%; high level of effective call attempts: more than 60%. See Rccoiiiiiiendation E.600. 1 Recommendation E.426 (10192)
