asterisk users - Sep 2006 - sangoma A104d echo canceller and fax

Hi!

I have a sangoma A104d and have some questions about the echo canceller. 
Maybe someone can answer by questions.

1. EC can be activated with wancfg and in /etc/asterisk/zapata.conf. 
What is the difference? I have some suspicions - can someone confirm or 
correct this?

   wancfg: hw echo cancel = yes
   zapata.conf: hw echo cancel = yes
chan_zap activates an echo canceller. As there is an hw echo canceller, 
this is used instead of the SW canceller

   wancfg: hw echo cancel = no
   zapata.conf: hw echo cancel = yes
chan_zap activates an echo canceller. As the hw echo canceller is 
disabled the software EC is used

   wancfg: hw echo cancel = yes/no
   zapata.conf: hw echo cancel = no
chan_zap does not activates any echo canceller.

Is this correct?

2. During Fax transmissions the EC should be disabled. IIRC there is a 
deubg message similar to "fax tone detected, disabling echo canceller 
...". I made some tests with Fax and activated EC. In log messages I see 
that the EC is activated as soon as the call is connected, but there is 
no log message that a fax is detected and the EC is disabled.

How can I disable the EC during fax transmissions?

Thanks
Klaus