The FDCPA has an express requirement for sending of collection (dunning) notice, in recognition that reporting to a CRA is not sufficient identification of the debt, the current creditor, or advisement of debt validation rights.

The information needed should have been conveyed via dunning notice within 5 days after their credit reporting. FDCPA 809(b).

Did you receive dunning notice?  Request debt verification within its 30-day period, being sure to additionally request the name and address of the original creditor.