ITU-T Rec. E.164 (1991) NUMBERING PLAN FOR THE ISDN ERA
FOREWORD
1 Introduction
2 Definitions
3 National numbering plan
4 Limitation of the number of digits to be dialled by subscribers
    4.1 International number
    4.2 National (significant) number - pre-time T definition
    4.3 Digit capacity of international registers - pre-time T
    4.4 Structure of the international ISDN number
    4.5 Number length - post-time T
5 Prefixes and codes
    5.1 Applications
    5.2 Country code 8), 9)
    5.3 Assignment of country codes
    5.4 Codes for new international services
    5.5 Trunk prefix 8)
6 ISDN numbering plan principles
    6.1 General
7 Numbering allocation principles
8 Network identification
9 Service identification
10 Calling/connected line identity
11 Dialling procedures
12 Addressing within a subscriber's installation
    12.1 Addressing by an ISDN number
    12.2 Sub-addressing (network address extension)
    12.3 Combination of addressing and sub-addressing
    12.4 Address delimiters
13 Recommendation history
ANNEX A List of country codes incorporating amendments proposed by the World Plan Committee, 1988
ANNEX B Rules for the assignment of spare country codes
ANNEX C List of spare country codes for the international semiautomatic and automatic service
ANNEX D Guidelines for NDC application
ANNEX E Alphabetical list of abbreviations used in this Recommendation