A non-breaking thin space (called a ‘period’) should be used between chunks of digits. This makes it easier to read the telephone number and prevents ‘clunky parentheses.’
Also, periods take up less horizontal space than a dash or a space. However, simplification only sometimes increases readability. This is particularly the case with phone numbers.
Use dashes and brackets.
Dashes signal an interjection or pause in your writing, while parentheses introduce additional information to your sentence. Both marks must be used sparingly; if overused, they can confuse your readers and ruin the flow of your thoughts.
If you are writing for an international audience, always use the internationally accepted format, which requires a plus sign (+) followed by a country code, a space, and the remaining digits. If you need help with the correct international format, contact your local telecom provider or consult the content guide that comes with your phone.
Many people prefer to use em-dashes for phone numbers, but em-dashes are only recommended if you are indicating an omission of words from a direct quote or if you need to add emphasis. Em-dashes can look overly casual in formal academic research and must be clarified for the reader if not used sparingly. This caution extends to instances involvingย letters in telephone numbers, where clarity and appropriate usage are essential.
Use periods
National conventions for expressing phone numbers vary; some countries use periods instead of parentheses or dashes. Periods save space and are consistent with the widths of hyphens in most font designs.
On the other hand, periods have a drawback: they visually separate the segments of a phone number, making it more difficult to read. This might be a big drawback when writing something that tries to be clear and concise. A final note: when using a date in running text, spell out months nine and up and use numerals for the rest.
Use hyphens
Use hyphens to separate the parts of a phone number. Avoid using parentheses, periods, or spaces to separate parts of a telephone number, as this will confuse your reader. The format of a phone number will vary by country, so it’s best to consult your localization style guide to find out how to format the number in your country.
When writing numbers, spell out the digits nine and below and use figures for those above 9. A hyphen should be used when using a number as a noun or adjective.
Hyphens also mark ordinal numbers (one, two, three, etc.). In this case, you should drop the hyphen when combining the numerator and denominator: She completed two of the five-page report.
Use commas
Use commas to separate numbers in the same group and pronounce them similarly. This makes reading the numbers on the phone easier and helps them understand what the number means.
A comma is also used when listing prices or costs for items. This is particularly important when a single mention of the amount or large rounded sums over a million are mentioned. This is also important for screen readers.
Commas should be avoided when linking two stand-alone sentences unless a coordinating conjunction connects them. This is a mistake known as aย comma splice. Also, avoid using a comma after clauses that add information to the sentence but aren’t essential for its meaning.
Use spaces
When writing aย phone numberย in a letter, use non-breaking thin spaces between chunks of digits. This ensures that the number will stay together if it is shortened or printed on narrow lines and prevents misreading of digits where they are written in lowercase (also called old style or lining numerals).
When mentioning time or dates, include AM or PM and the date itself. Also, for days/periods, use a spaced en dash rather than an em dash.
For content that will be used internationally, follow the local format for your country.
