Billing Models allow an Administrator to define how to compute charges for their customer Facility.  This is performed on the Administration tab under Billing Models.  Both units (such as a 65-character line) and rates (such as 12 cents) are specified in a Billing Model. 

Multiple Billing Models can be used for a Facility, but only one can be the default.  This default model is loaded each time the Billing Reports screen is populated.  

For more information on how to create a Billing Model, please see "How to Create a Billing Model" KB234.  See KB808 for details on setting up a Tiered Billing Model (currently in limited Beta release).