Collection agencies that specialize in collecting consumer debts, such as Portfolio Recovery Associates, L.L.C., or Rapid Recovery Solution, Inc., are considered debt collectors. Even law firms who regularly engage in the business of collecting consumer debt, such as Forster & Garbus LLP and Zwicker & Associates, P.C. are considered debt collectors.
If the original creditor is contacting you directly (American Express, Citibank, etc.) then they most likely WILL NOT be considered debt collectors for FDCPA purposes.