asterisk users - Jun 2003 - digium drivers for ISDN card

i read that quite all of you are using the driver for the isdn that
you are using is the digium... i use I4L and i got a problem with some
call through normal PBX, can someone tell me where i can download the
digium drivers for the ISDN card?
i didn't find it... but i'd like to try if is a driver issue...
(i use a digium isdn card...)

thanks a lot,

 Angelo