Check out an earlier case of worldcom long distance resale sending out bills they can't collect.
http://www.forbes.com/forbes/2002/0610/064.html
"Ring of Thieves" by Neil Weinberg, 06.10.02
Ring of Thieves
by Neil Weinberg
A former MCI billings manager sits in a federal prison, convicted of crimes he said he learned to commit while working for his former employer.
this one resulted in 600 million write off in 2000