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Classes define the type of usage (e.g. data, sms, etc.).
Rate Group: Setup → Usage Rating → Usage Rates → Groups
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Add Package: Account → Profile → Packages → + 
Account Package
Packages are products/offerings that are added to accounts and billed. When you add a package to an account it will indicate when it will next be billed by showing a ‘Next Bill Date’ value.
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Bill Account: Account → Profile → Packages → $ Bill Account
On the packages screen there is an option to bill packages (theaction button). This will allow you to bill the account package added in the step above. Provided the bill run date range is configured to bill over the package’s ‘Next Bill Date’ and the options on the bill run are set to bill packages, run invoices and render invoices.
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