https://daringfireball.net/linked/2026/04/16/how-to-format-10-digit-phone-numbers
How to Format 10-Digit Phone Numbers
By John Gruber
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The Associated Press Stylebook, on Threads:
We updated our style for telephone numbers in 2024 to drop parentheses. We now recommend the form: 212-621-1500.
For international numbers use 011 (from the United States), the country code, the city code and the telephone number: 011-44-20-7535-1515.
Use hyphens, not periods. No parentheses. The form for toll-free numbers: 800-111-1000. If extension numbers are needed, use a comma to separate the main number from the extension: 212-621-1500, Ext. 2.
I have long been annoyed that U.S. phone numbers are so often formatted in the outdated (123) 555-1234 format. The use of parentheses for the area code dates back to the old days, when you only needed to dial the area code to call a number outside your own area code. (The same era whence comes the verb dial.) Until 10-digit dialing with mandatory area codes started to become standard in the late 1990s, you only needed to dial seven digits to call a local number.
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Never realized that this was a problem. But it is annoying when filling out forms, cut’n’pasting data, and interchanging fields.
I’d agree with the author mostly except of the extensions. I’d prefer just the comma and number. I remember using it on autodialers back in the old telephone modem days.
We need open standards that everyone uses!
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