The USA country code for faxed documents is "+1," which denotes the North American Numbering Plan area. When sending a fax from outside the U.S., first dial the international calling prefix, which is "011" for the United States, then the country code, which is "+1," and finally the fax number.
Fax Authority states that other locations grouped in the North American Numbering Plan include Canada, the British Virgin Islands, Jamaica, Puerto Rico, Trinidad and Tobago, Bahamas, the Cayman Islands and many more. The countries within the NANP all take the same steps for international faxing as the USA: "011" + "1" + area code and fax number. Each country in the NANP is also given an area code as though they all were in one country.