To my knowledge Southwest doesn't sell such a 'voucher' product, though. It seems possible that this company was just selling 'vouchers' and, when it came time

To my knowledge Southwest doesn't sell such a 'voucher' product, though. It seems possible that this company was just selling 'vouchers' and, when it came time to fulfill the 'voucher', they were just buying a plane ticket with cash. You could get away with this for a while by booking flights only for the people who wanted the least expensive itineraries and only on sale … and by taking in new money promised against future months to pay for the current month's sales.