John Gruber points out an AP Stylebook update posted on Threads:
We updated our style for telephone numbers in 2024 to drop parentheses. We now recommend the form: 212-621-1500. … Use hyphens, not periods. No parentheses.
John comments,
I have long been annoyed that U.S. phone numbers are so often formatted in the outdated (123) 555-1234 format.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.
John’s right, though I tend to prefer the European custom of using periods or spaces to separate the parts of the phone number instead of the AP’s hyphen. Smaller marks are less distracting to my eye.
I can remember a time and place when five-digit dialing was still available. For a couple years in the late 1980s, my family lived in a small town in Maine with an old (even for that time) phone switching system. It did not offer tone dialing, so we had to switch back to a rotary phone. Also, if the exchange for the number you wanted to call had the same first two digits as the line you were calling from, you could connect by dialing just the last five digits. (So, you could dial “234-5678” by dialing just “4-5678.”)