866 numbers: who called me?
Free for the person calling.
866 is a toll-free prefix introduced in 2000. Calls to 866 numbers are free for the caller.
866 is used by many national organizations and call centers. Like all toll-free codes, it does not show a location, and the same prefix is used by honest businesses and by robocall campaigns.
The most useful check is the full number, not the prefix. Look it up, read what others report and, if you are unsure, call the organization back on a number you found yourself.