[Asterisk-Users] Ugly echo cancel, with Bristuff/Zaphfc

[Pisac]

I'm using bristuffed Asterisk with ISDN/ZAPHFC
I have VERY ugly (outgoing) sound through ISDN/HFC if echocancel=yes in
zapata.conf, but without echocancel I have bad (incoming) echo
Through PSTN/FXO sound is ok with or without echocancel.

I tried other echo cancellers (in zconfig.h) two times:

ECHO_CAN_KB1 (this was default)
ECHO_CAN_MARK2
ECHO_CAN_MG2

after any change I compiled (make clean all && make install) all drivers
which are bristuffed, without recompiling Asterisk (should I?), but...

... I always have EXACTLY same (ugly) sound and same (appearing of) echo
cancelling.

Seems to me that echo canceller do not changing no matter what I choose
in zconfig.h. This must be some bristuff echo cancel "patch" to zaptel
source? Before I bristuffed Asterisk, I was playing with zconfig.h and I
remember that difference between echo canceller were very obvious.

Anybody have some knowledge about bristuffed echo cancelling?