Area code 866 does not cover any particular location. Area code 866 is used for toll-free numbers, specifically those in countries covered by the North American Numbering Plan.
The North American Numbering Plan encompasses 25 countries and territories in North America and the Caribbean. All telephone numbers in this plan consist of a three-digit area code, a three-digit central office code, and four-digit station number. The area code 866 is similar to other prefixes such as 800, 844, and 888, which are used as toll-free numbers. Individuals calling numbers that have any of these prefixes, including area code 866, call the number free of charge, as the owner of the telephone number is responsible for the cost.