Once each call is rated, this information is stored until the invoice is run, usually once a month in North America. When the invoice is run, other nonusage charges can be applied to the bill, such as volume discounts or monthly fees. This information is then prepared so that it can be printed in a readable form. Finally, the envelope is printed, stuffed with enclosures, and mailed. Call data is also shared between companies to handle calls that originate, terminate, or are transported on another company's network.
Several options are available that change the nature and capability of the billing system.
For example, if calls are rated and stored, then an accurate current bill total can be quoted to a customer. Unfortunately, this limits the option to provide flexible ratings based on volume of usage. However, that call data might be useful for studying usage patterns. Data formats, especially among different billing system components, are a significant source of complexity and expense in any system. Data that is shared is particularly sensitive to compatibility issues.