The fair debt collection practices act applies to both "consumers" and "debt collectors."
Consumers are only covered in personal and family or household transactions. Any transactions relating to a personal business are not covered under the fair debt collection practices act.
Debt collectors are defined as: "any person who uses any instrumentality of interstate commerce or the mails in any business the principal purpose of which is the collection of any debts, or who regularly collects or attempts to collect, directly or indirectly, debts owed or due or asserted to be owed or due another."