800Notes.com is the largest user-supported database of unpublished phone numbers.

The majority of the phone numbers used by banks, credit unions, insurance companies, non-profit organizations, telemarketers, or collection agencies are not published. So instead of wondering who is calling and deciding whether you should keep ignoring or return the calls you can go to 800Notes.com, enter the phone number into the search field and read what others have to say about the caller.

If it’s a telemarketer, users often share ways to opt out. If it’s a collection agency, you can find their name and contact information provided by the community. If the caller says you’ve won a free trip to Las Vegas, a quick search will prove that’s likely not the case since a couple hundred people have reported the same.