Journalists adhere to style guidelines when writing articles; those most often used are found in the Associate Press Stylebook, which is updated on a yearly basis. There are specific stylistic instructions for weights, measurements, parts of speech and usage. Phone numbers are no exception. The AP Stylebook indicates a particular method for including this information in journalistic writing.
Place the area code within parenthesis. For example, a Lexington, Kentucky phone number would begin with (859) when using AP style guidelines.
Include a space between the area code and the local prefix.
Separate the local prefix and the last four numbers with a dash. When finished, the AP formatted number should look like this: (859) 425-2255 -- which is the main number for the Lexington-Fayette County Urban Government.
Format toll free numbers in the same manner outlined as above, placing the 800 number area code in parenthesis, inserting a space, and then separating the local prefix from the last four digits with a hyphen.
Abbreviate the word "extension" and separate it from the phone number with a comma when including a telephone number with an extension, such as (859) 555-1212, ext. 6731.
Insert the country code and, if necessary, the city code in parenthesis, such as (44-20) 7353-1515, for international phone numbers.