Areacodehelp.com indicates that area code 855 is not assigned to a geographical area. Rather, the code is used for toll-free calls, meaning the phone charges are paid by the receiver instead of the caller.
Calls made to toll-free numbers, including area code 855, can be restricted by the customer. The number 855 was put into service on July 29, 2000. Other toll-free area codes include 800, 844, 866, 877 and 888. The FCC regulates the use of toll-free numbers and the numbers are assigned by the North American Numbering Plan. As of 2015, area codes 822 and 833 are reserved for toll-free numbers but are not currently in service.