Digium, Inc.
Page 15
Chapter 1: Overview
Echo-Cancellation
Users connecting their Analog 410 Series cards to the PSTN or other
devices are likely to be placing calls that will result, at some point, in an
unbalanced 4-wire/2-wire hybrid. The result of this hybrid is the
reflection of a near-end echo to the calling party. Elimination of this echo
is the responsibility of echo cancellation.
The Analog 410 Series cards, unless otherwise equipped, utilize Asterisk
to perform software-based echo cancellation. Asterisk maintains a
number of open source echo cancelers. These open source echo cancelers
provide a moderate level of echo cancellation, but are not capable of
dealing with higher levels of, or more advanced, echoes.
Digium recommends that those users concerned about echo cancellation
purchase the VPMADT032 hardware echo cancellation module. The
VPMADT032 may be combined with both the TDM410 and AEX410.
The VPMADT032 is designed to handle up to 128ms of echo cancellation
across all channels and provides a G.168 echo cancellation solution.
