asterisk users - Feb 2004 - Carrier Access Access Bank 1, incomming calls only echo problems, and Adit 600

I am a little confused about the FXO ports on the Carrier Accesss Bank 
1. The wiki, and people on the mailing list have stated that they do not 
have impedance matching, but Carrier Access states in their 
documentation that they do have impednace matching. Did Carrier Access 
make a typo, or does it depend on the version of the FXO card?

I current have a CAC AB1, and I am having echo problems with analog and 
sip phones. I have echocancel=128, echocancelwhenbridged=128, 
echotraining=yes,  in zapta.conf. 128 taps for echocancel does the best 
job for my system... I've adjusted the rx gain and the tx gain to the 
lowest possible, and stilll be usable. I've ran a brand new cat5 from 
the dmark. And I still have echo problems on incoming calls only; 
outgoing calls are perfect.

Would a Adit 600 help with the echo problems? Even if the CAC AB1 has 
impedance matching would the Adit 600 help? a partial T1 is too much 
from the local telco, qwest, because we only have four lines...

--Spencer