1、INTERNATIONAL TELECOMMUNICATION UNION ITU-T TELECOMMU N CATION STANDARDIZATION SECTOR OF ITU TELEGRAPH SWITCHING GENERAL u.7 (03/93) NUMBERING SCHEMES FOR AUTOMATIC SWITCHING NETWORKS ITU-T Recommendation U.7 (Previously “CCIlT Recommendation”) ITU-T RECMN*U-7 73 4862573 0586172 OT2 FOREWORD The ITU
2、 Telecommunication standardization Sector (ITU-T) is a permanent organ of the International Telecom- munication Union. The ITLJ-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide b
3、asis. The World Telecommunication Standardization Conference (WTSC), which meets every four years, established the topics for study by the ITU-T Study Groups which, in their turn, produce Recommendations on these topics. ITU-T Recommendation U.7 was revised by the ITU-T Study Group IX (1988-1993) an
4、d was approved by the WTSC (Helsinki, March 1-12. 1993). NOTES 1 As a consequence of a reform process within the International Telecommunication Union (ITU), the CCIT ceased to exist as of 28 February 1993. In its place, the ITU Telecommunication Standardization Sector (ITU-T) was created as of 1 Ma
5、rch 1993. Similarly, in this reform process, the CCIR and the IFRB have been replaced by the Radiocommunication Sector. In order not to delay publication of this Recommendation, no change has been made in the text to references containing the acronyms “CCITT, CCIR or IF” or their associated entities
6、 such as Plenary Assembly, Secretariat, etc. Future editions of this Recommendation will contain the proper terminology related to the new IT structure. 2 telecommunication administration and a recognized operating agency. In this Recommendation, the expression “Administration” is used for concisene
7、ss to indicate both a o ITU I994 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. ITU-T RECMNW-7 93 4862593 058bL93 T39 m Recornmenda
8、tion U.7 NUMBERING SCHEMES FOR AUTOMATIC SWITCHING NETWORKS (Former CCIT Recommendation E. 7, Geneva, 1956; revised Helsinki, 1993) The CCITT, considering the plan for telex destination codes contained in Recommendation F.69; that with fully automatic working between subscribers of the international
9、 telex service it is desirable to envisage the possi biii ty : a) of routing traffic over the appropriate international trunk route where more than one such route exists between two countries; b) of enabling the appropriate tariff to be determined automatically (in the originating country), even if
10、the destination country is divided into several tariff zones, unanimously declares the view (1) that national numbering plans should be systematically arranged; (2) that, where more than one international trunk route exist between two countries, the corresponding geographical division and hence the
11、appropriate point of entry should be identifiable by examination of the initial digits of the called subscribers national number; (3) country by the initial digits of the called subscribers national number; that, where a multiple tariff scale exists, the different tariff zones should be identifiable
12、 in the originating (4) that the number of initial digits of the subscribers national number to be examined for routing purposes should be limited, to one, but in any case should not exceed two. When a single digit provides the discrimination it will usually be the first digit, but, where the subscr
13、ibers national numbers have a uniform initial digit (usually O) to permit discrimination on national calls, the following (second) digit should be used; NOTE - The attention of Administrations (and recognized operating agencies) is drawn to the considerable technical advantage that would result from the adoption of a single tariff between two countries. (5) national number does not exceed 12 digits in accordance with Recommendations U.11 and U.12. that the national telex numbering plan should be arranged in such a way that the destination code and the Recommendation U.7 (0-3) 1
