A call tag is a type of prepaid return label that can be attached to an item for return. It is usually given by companies so that a customer can return merchandise via mail without the need to purchase another label. UPS offers UPS Return labels, rather than call tags.
Return labels are considered a value-added service and have an additional cost, often assumed by the company that shipped the item. UPS currently offers three kinds of return labels: the Print Return Label, which is usually printed by the company; the Electronic Return Label, which is emailed to the customer; and the Print and Mail Return Label.