Area code 866 is a toll-free number that is not assigned to any geographical area. It is often assigned to telephone numbers used for customer support and technical assistance within a business or other organization.
For toll-free numbers such as 866, the caller does not pay for the cost of the call. Any charges for the call are borne by the party being called.
The 866 area code was put into service on July 29, 2000. As of August 2014, other toll-free area codes include 800, 844, 855, 877 and 888. Future toll-free area codes are 822 and 833. They are not in service, as of August 2014, and an implementation date has not been established for either area code.