Paul Makepeace ;-)

How to write a phone number

Phone numbers are often written in a way that deletes or distorts information about them. The most common error I experience day to day is people simply not understanding what London's area code is. (Hint: If you think it's 0207 or 0208 you definitely need to read this.) The other common stylistic issue is the US tendency to write their phone numbers like (831) 238 0902. You'll see shortly why this is a problem on a number of levels, not least that that phone number doesn't actually work.

This is a first draft; might beef it up a bit later. In particular I only talk about the UK and US as they're the only two systems I know much about. Additions very welcome!

Skip down to the solution.


A phone number consists of a country code, area code, and phone number. Only since the 21st century has the general public paid much attention to the country code.

For example,

UK44208870 9929
US1831238 0902

So anywhere in the world, so far as I know, those numbers will uniquely identify a phone number. The only additional piece of information required is the international prefix: the digits required to dial outside the country.

National and international prefixes

International phone calls require the international prefix which depends on the country you're dialling from. From the UK it's 00; from the US 011.

So a full international number is

international prefix + country code + area code + phone number.

For example, to dial our UK number from the US we would use 011442088709929. Dialilng the US number from the UK number would be 0018312380902.

To dial a number in the same country as you're dialling, you use the national prefix + area code + phone number. For example in the UK the national prefix is 0 so the number above would 02088709929.

Viva la différence

Each country has its own way of writing a phone number. For example, in the US the country code is generally omitted and the area code parenthesized, like so (831) 238 0902. Which is odd, since that number won't actually work if you were to dial it: you need the national prefix 1 (which coincidentally is the same as the US's country code–ah, the joys of being the first to get it all working).

In fact, in some places like Houston, Texas dialling other numbers in Houston you actually have to dial those ten digits. The area code in a "ten digit dialling" number is now a required part of the phone number so for example even in area code 713 you'd need to dial 713 555 1212. In the US it's common to see the area code written parenthesized even though technically in the case of ten digit dialling this is wrong since it is no longer optional. (Assuming you read "( ... )" as denoting something is optional.)

As we've just seen, the UK doesn't use parentheses but instead melds the national prefix into the area code, e.g. 020 8870 9929.


What about the spaces in numbers, why 238 0902 versus 23 80 902? It's purely local convention and has no impact when dialling–there is no "space bar" on a numeric keypad. Spaces are generally used to separate country, area, and phone number. Additionally some a space is thrown into the mix of 7+ digits to visually break it up a little. We'll see shortly how this can cause problems. Talking of which...


Even between just two countries we have,

So we need some solution that addresses all the above problems. Let's first examine where spaces in phone numbers may occur.


Or, A rant about writing "0207", "0208", "01179", etc

The spacing in particular causes problems of its very own. Imagine doing something as absurd as putting a space in an area code, and then even more perversely, transferring one cleaved part of that severed area code onto the phone number?! Or, vice versa, lopping off a part of the phone number and bonding it willy-nilly to the area code. Completely ridiculous most would agree - an area code is an area code, if you add digits to it it ain't the area code any more. Imagine delivering mail to your house with an extra digit in the house number. Or, worse, adding digits to the postal code.

But guess what, in the UK this is what millions of people are doing. Even a practice the incumbent telecoms provider, British Telecom, was engaged in. That's right, the biggest phone company in the UK, did not until quite recently (2002?) accurately write phone numbers on its customers' bill. I'm hoping this is the fundamental reason why so many people in the UK still make this mistake, as opposed to for example the population of Britain being a bunch of clueless numbskulls. :-)

By this point it should be becoming clear what is wrong with "0208". There's a suggestion that 208 is the area code. It is not. 20 is the London area code. (In fact one of the major points of transitioning from the old London area codes, 171 and 181, was to enable direct dialling to any of London.) The 8 is part of the phone number. If you were to deduce from 0208 870 9929 that the number 870 9929 was the phone number and dial it within London you would simply not get through; the exchange waiting for the final eighth digit. You'll see similar errors with say Bristol whose area code is 117, numbers wrongly written as 01179 246371.


Write your phone number, always, like this:

+44 7814 728381
+44 20 88709929 (or +44 20 8870 9929)
+1 831 2380902 (or +1 831 238 0902)

where + denotes "whatever the country you're calling from's international prefix is".

So the solution requires knowing two pieces of information: how to dial internationally, and nationally. This is incredibly basic information provided on payphones, in phonebooks, and besides that almost everyone capable of actually using a phone could explain.

Reasonable alternatives

Including the national code like this,

+44/0 7814 728381 (preferred)
+44/(0) 7814 728381 (in semi-common usage now)

The US's national and international codes are the same so have the elegant solution of simply +1 831 2380902.