What to do if a collection agency is calling but not getting their address online?
You can tell the collection agency to share the details of their physical address or the website. You should also ask them to validate your debt before you start negotiating or make any payments.
Generally, you know which debt collectors you owe because they send letters or list your accounts on your credit report.
They might be fake collectors since genuine debt collection agencies have proper mailing address or contact details. In case you don't get the phone number online or have lost the letters, then ask the original creditor. Or, wait for the debt collection agency to contact you again.