[asterisk-users] Echo problem

[Scott Gifford]

Hello,

We're in the process of setting up an Asterisk server, and are having
echo problems.  We have a Digium TE110P, and have tried the MG and
MARK2 AGGRESSIVE echo cancellers, with a variety of gain levels and
training times, and with both trunk and 1.2 branch versions of
Zaptel, Libpre, and Asterisk.  In all cases, callers from the PSTN
hear their own voice echoed back after 1.5-2 seconds; none of these
adjustments made a difference, except adjusting gain made the echo
quieter.

We followed these instructions in trying to eliminate echo:

    http://www.asteriskdocs.org/modules/tinycontent/content/docbook/current/docs-html/x1695.html

Our lines come in from the telco in a PRI, then connect to a Tadiran
switch which hands the lines off to Asterisk over a T1 card.

We have done loopback tests with the Digium card with a loop plug in
it.

We're a bit stumped as to what to try next.  Any suggestions or
advice?

Thanks

---Scott.