�1����
Scope
�2���� References
�3���� Terms and definitions
�4���� Abbreviations
�5���� Bearer capabilities for which echo
control is required
�6���� Arrangements of echo control
devices with respect to signalling
�7���� Operation without signals
�8���� Considerations for the need of
ECDs
������� 8.1���� Information taken into
consideration
������� 8.2���� Propagation delay counter, call
history information
�9���� Functions of an exchange
initiating echo control
10���� Unavailability of echo control devices
11���� Placement of echo control devices in the network
12���� Handling of echo control devices in the case of different bearer
capabilities
13���� Other considerations
Annex A - Echo control logic
������� A.1���� General principles and definitions
����������������� A.1.1���� General principles
����������������� A.1.2���� Definitions
������� A.2���� Abstract model
����������������� A.2.1���� General description
����������������� A.2.2���� Signalling system/protocol
����������������� A.2.3���� Interworking
����������������� A.2.4���� Special network nodes
����������������� A.2.5���� Echo control logic
������� A.3���� SDL diagrams
Appendix I -
Transmission of echo control information elements via signalling systems