asterisk users - Jul 2006 - zaptel Disabled echo canceller because of tone (rx) on channel 2 work?

All greetings. If I have correctly understood, echocancel algoritms
prevent to go to fax-messages. Therefore at detection of attempt of
reception or transfer of a fax-message, echocancel on a line it is
disabled, in /var/log/messages thus appears such messages zaptel
Disabled echo canceller because of tone (rx) on channel 2. At me a
problem that detection of a fax or some reason works very seldom as
consequence faxes go very badly. For a week of work, echocancel
disables 2-3 times, thus every day is accepted and sends tens
fax-messages. As experiment I included in/etc/zapata.conf
faxdetect=yes on a line. At sending or reception of a fax, the line
understood it very quickly. How it is possible to improve reaction of
a line to faxes that echocancel disabled always?
Sorry for my bad english and thanks for help.