Prepare purchase orders and send copies to suppliers and to departments originating requests. Determine if inventory quantities are sufficient, ordering more materials when necessary. Respond to customer and supplier inquiries about order status, changes, or cancellations. Perform buying duties when necessary. Contact suppliers in order to schedule or expedite deliveries and to resolve shortages, missed or late deliveries, and other problems. Track the status of requisitions, contracts, and orders. Calculate costs of orders, and charge or forward invoices to appropriate accounts.