A debt collector is covered by the Act if their principal purpose is the collection of the debt; the fact that they are also the creditor does not preclude a finding that debt collection is the primary purpose of the organization.
http://www2.ca3.uscourts.gov/opinarch/172851p.pdf
Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Neither an authoritative statement of the law nor legal advice. Quick work.