[Asterisk-Users] very big Echo, isdn -> isdn

[Corvin]

Hi,

I'm in big trouble I've got two serwers with Asterisk 1.03 both serwer with 2 
ISDN cards. When I call isdn server card and then choose other msn (disa)
I can make connection with other phone (I've got standard ISDN PBX).
But echos are horrible. 

My configuration:

Athlon 2.0
256 RAM 
2 HFC cards
i4linux.
mandrake 10.1 kernel 2.8.1

and second server

Celeron 2.6
256 Ram
2 Winbond based ISDN cards
I4linux.
slackware kernel 2.4.26

Especially on the second server I have echo after one second,
I looks like something records sound and play it 1,5 sek after I say 
something. I'm looking for solution.
Any help? Many thanks in advance.

BR,
Corvin