Rec. ITU-T G.101 (11/1988)  – THE TRANSMISSION PLAN
1 Principles
2 Definition of the constituent parts of a connection
    2.1 The international chain of circuits and the national systems
    2.2 National extension circuits: 4-wire chain
3 Number of circuits in a connection
4 Incorporation of unintegrated digital processes
    4.1 General
    4.2 Types of telephone circuits
    4.3 Number of unintegrated PCM digital processes
    4.4 Transmission of analogue and digital data
    4.5 General principle
5 Conventions and definitions
    5.1 Virtual analogue switching points
    5.2 Relative level specified in the virtual analogue switching points of international circuits
    5.3 Definitions
    5.4 Interconnection of international circuits in a transit centre
References