�1���� Introduction and scope
�2����
Definitions
�3����
Effect of listener echo
������� 3.1���� General
������� 3.2���� Effect on voice transmission
������� 3.3���� Effect on voice-band data transmission
������� 3.4���� Effect of listener echo in a connection with multiple 4-wire
loops
�4����
Limits of listener echo
������� 4.1���� Voice transmission
������� 4.2���� Voice-band data transmission
References