1
Scope
2 References
3 Definitions
4 Abbreviations
5 Requirements/Principles
6 Conceptual Model
7 Network Architecture
7.1 E1-Network
7.2 T1-Network
8 International Switching Centre
9 External Echo Control Device
10 ECD control channel
10.1 E1-Network
10.1.1 Requirements for the control channel equipment
10.1.2 Coding
10.2 T1-Network