asterisk users - Nov 2004 - isdn to isdn data call (bristuff'ed with hfc based card)

Hi,

anyone try to setup data call from one hfc-isdn card to another (across 
asterisk) ?

I can't establish isdn data call from isdn modem -> hfc card 
->asterisk->hfc card-> telco isdn line
voice call working great , only some echo problems.

any idea? maybe something in dialplan ?

tnx,
Tomaz