Holy cow, I think I know what those circuit cards were for! Our switch has an A/B card system that operates hundreds of line cards. If the A card malfunctions (always does), the B card kicks in and handles the call switching. Then the 'system' put the A card back on line that night only to fail again the next day during high call volumes. I keep asking WTF, why we don't replace the damn A card and the frame guy tells me its 80 grand and there are none available.