How to Format Phone Numbers

Fri, 24 Apr 2026 10:25:12 +0800

This piece is inspired by this post on daringfireball, which, in turn, was inspired by AP’s style guide on phone numbers.

Their post is about where parenthesis goes in phone numbers. I don’t care much about that. What I care about is the fact that there is an international standard for phone numbers that they’re not using.

For international numbers use 011 (from the United States), the country code, the city code and the telephone number: 011-44-20-7535-1515.

No.

The correct way to format an international number is: +44 20 7535 1515. You can use dashes, or spaces, or dots, or whatever. That’s style. AP can have their opinion on that.

The +44 bit, however, is substance. Countries have different international dialling codes. As is traditional, the US variation is different from almost everywhere else.

Why does it matter? If I store my numbers in my phone with the + country code format, the numbers work wherever I am in the world! If I’m in the US, the system will replace the + with 011. If I’m in the UK it will use 00. Similarly, if someone calls me, my phone can correctly look up the number in my address book¹.

But, you say, my phone does work! Kind of. It has to jump through some hoops and use various heuristics to correctly guess the country code and convert numbers on the fly. It would all work so much more smoothly if numbers were stored with the… normal format.

If your numbers are purely for a domestic audience, then I suppose that using the APs guide might be okay. However, whenever I share my number, I almost always use the international format. It’s not that much more work. It works everywhere. That feels like a small price to pay.

At work we use a HR system that has a plugin that works with the phone app, allowing caller ID for any employee. It’s a nice idea but it almost never works for US employees, who almost always enter their numbers in US rather than international format. ↩︎

This is ZX81.org.uk

How to Format Phone Numbers