ISDN Faults .. I always seem to fix them by Loading the latest firmware , Default the system .. push the cards back in "IN PORT ORDER!", DO NOT up load the old database , do "Partial ONLY" upload 11-xx,15-xx,21-xx,22-xx,30-xx, ONLY , hand program the rest .. this has fixed quite a number of ISDN faults, in my opinion there seems to be a few MB's maybe timers that some how get corrupted from time to time & it would be like finding a needle in a hay stack... if all else fails might be worth a try ....
Joel