As of 2015, a number of countries use the 011 code, including the United States, American Samoa, Anguilla, Barbados, Canada and Granada. Other countries using the code include Jamaica, Northern Mariana Islands, Saint Vincent and the Grenadines, Dominican Republic and the United States Virgin Islands.
The 011 code is used by any country that falls within the North American Numbering Plan, or NANP. The NANP is a telephone numbering plan that includes approximately 25 regions and countries in North America. The system was initially created to unify older local numbering plans. 011 is one of many international call prefix, or dial out codes, used to place an international call. It relies on an international telephone circuit to place the call, and the prefix for must be dialed before dialing the remainder of the number.