Translation: We want to get you sued for some old debt, or at least make you think that's imminent.
The extreme secrecy is due to a long running legal conflict between the twin mandate for both privacy and disclosure. It is a stupid message, but it's meant to keep the collection agency from getting sued itself.
Whether you are called a debtor or some collector thinks you can flush one out, you have rights and options. Most are simple to exercise if you only learn how. The FTC and the CFPB can start you on your homework. See also if your state laws grant additional or stronger rights.
official FTC guidance and staff opinions on the FDCPA, PDF copy of the Act
CFPB reiteration of the Fair Debt Collection Practices Act