Chapter 6: Transmission Considerations; Contents; Echo - Avaya Communication Server 1000 Series Reference

Chapter 6: Transmission considerations

Contents

This section contains information on the following topics:

Echo

on page 29
Loss on page 30
Tandem switching
Trunk routing rules
Gain on page 31
Echo
All voice connections between telephones require two directions of transmission for
conversation to take place. When the signal transmitted in one direction reflects over the other
directional path, the caller hears the caller's own voice, with a slight delay.
Depending on the delay, the effect is perceived as sidetone, rain barrel effect, or echo. Two-
wire facilities require care in matching impedances to prevent reflections. Four-wire facilities
neither generate reflections, nor eliminate reflection in built-up connections, because in most
cases, there are 2-wire connections to the telephones.
The objection to echo increases with echo delay. The Via Net Loss (VNL) plan increases loss
depending on delay. However, the loss also reduces the received volume. Limits are placed
on the amount of loss used to suppress echo. If these limits are exceeded, use echo suppressor
devices instead.
Electronic Switched Network Reference — Signaling and Transmission
on page 30
on page 31
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