How to Write Fax Numbers

By Leyla Norman

Updated September 26, 2017

Fax numbers look the same as phone numbers.
i fax image by Ewe Degiampietro from

Fax number format is the same as that of regular phone numbers. Each includes an area code, a three-digit prefix, and four remaining digits. International fax numbers look a bit different from domestic fax numbers, but they do resemble international phone numbers. The main differences in how fax numbers are written revolve around how they are formatted and punctuated.

Write the area code of the fax number. Place the area code in parentheses, though this is not necessary. Write a hyphen or period after the last number in the area code with no spaces before it if you choose not to use parentheses.

Write the three-digit prefix of the fax number. Include a space after the right parenthesis of the area code if you choose to use parentheses around the area code. Leave no spaces after the hyphen or period if you choose to write the number without parentheses.

Write a hyphen next to the three-digit prefix if you used parentheses around the area code or if you wrote a hyphen between the area code and the prefix. Write a period next to the three-digit prefix if you have used a period between the area code and the prefix.

Place the four remaining digits of the fax number next to the hyphen or period. Leave no spaces between the hyphen or period and the four remaining digits. A completed fax number might look like (xxx) xxx-xxxx, xxx-xxx-xxxx or


An international fax number includes the international dialing code, the country code, the city/area code and the local fax number. For example, +xxx xxx xxx xxxx. Hyphens or spaces can be used between the numbers. The arrangement of the area/city code, three-digit prefix and four remaining digits will likely vary, depending on the country you are calling. Each country has its own preferred fax/phone number format. The number of total digits also may differ from domestic fax numbers. For example, 61 is the country code for Australia, and 880 is for Bangladesh.

Note that 011 is the U.S. international calling code. Dial this first to send an international fax from the United States.