Phony: Phone Numbers

ruby / phony / e164

This is a post about Phony 1.4.1+.


  1. Intro
  2. The Problem
  3. Phony
  4. Try it
  5. Internal API
  6. E.164
  7. Model/Representation Aside – in ActiveRecord
  8. Status
  9. Endnote 1
  10. Endnote 2
  11. Conclusion



You own a little startup, which has created apps that were only relevant for the domestic market. Until now.

Suddenly, the big breakthrough – your online car/music/housing/pet/houseboatlover’s website has been an overnight (5+ yrs) success, and people demand it be available all over the world, including customers from all over the world.

Coding goes very well, until suddenly one of your customers notices that their phone number is all awry. Instead of the melodious french 2-digit grouping 33 1 12 34 56 78, it is a horrible jumble of north american clumping: 3 (311) 234-5678. This is an outrage! Sacrebleu!

France invades the US on the very next day. Freedom fries are forbidden and … well, you know how the story goes.

This could all have been avoided if you had used Phony.

The problem

The big problem is that countries all over the world have different ways of splitting and formatting their phone numbers.

For example, Switzerland uses a 2-digit national destination code, like +41 44 123 12 12 – the 44 is the national destination code, which originally was geographic in nature, but isn’t anymore.

Germany is different in that it has a variable length NDC, from 1 to 5, for example Freiburg im Breisgau uses 3: +49 761 476 7676, and Berlin uses 2: +49 30 386 25454.

Denmark on the other hand has no NDC at all. And let’s not talk about Italy. No, let’s not.

You see? Big mess.

Well, there is some standardization called E164, and I’ll talk about it below. But first, Phony.


Phony does the ugly and dirty work of correctly formatting international phone numbers for you.

It can format, split, and normalize:

And it does it very fast. Each of these ops for 5 numbers is around 1 10’000th of a second on my MBP using Ruby 1.9.2.

Normalizing you use before saving a phone number into a database etc.

Splitting is helpful if you want to do your own special formatting, or remove certain parts.

Although that is probably not needed, as Phony can take care of that for you: Formatting render a number in international/national/local form, with zeroes, 00, plus + and special spaces, if you need them (" " is default).

Look at a few more examples.

Try it

First, get the gem: gem install phony


require 'phony'

p Phony.format('43198110', :format => :international, :spaces => :-) # => '+43-1-98110'
p Phony.split('33112345678') # => ['33', '1', '12','34','56','78']
p Phony.normalize('1 (703) 451-5115') # => '17034515115'

My country is not formatted correctly! What do I do?

Internal API

Sometimes I have a nice document to go on, most of the time I don’t, and not even in any of the languages or writing systems I know. Sometimes I simply made a mistake. This is where you can help Phony!

To add your “missing” country, fork Phony and look at the lib/phony/countries.rb file. It contains (almost) all the definitions. The more complicated ones – like Germany, Italy, etc. – are in their own files.

The internal API uses a little DSL to make managing and coding all the different formats easier.

The phone numbers of France, for example, have a very elegant structure:

country '33', fixed(1) >> split(2,2,2,2)

This says, that the country with country code 33 should have an NDC of fixed length 1, followed (>>) by a national code that is split in groups of 2.

As another quick example, the freshly added Slovakia:

country '421', match(/^(9\d\d).+$/) >> split(6) | # Mobile
               one_of('2')          >> split(8) | # Bratislava
               fixed(2)             >> split(7)

This says that Slovakia uses 421 as country code. If a phone number with NDC 9xx is found, split the national part into one big part with 6 digits. If not, go and check if the NDC is a 2, if yes, split it into a thing with 8 digits as national. If not, it must be a 2-digit NDC, with 7 digits following.


The description of what matching/splitting is available is at the top of the file.

First, add specs with a few example numbers, then fix, and send me a pull request. Get big thanks in the contributors entries. Try to beat Keith Bingman! :)

But let’s get back to phone numbers.


Or E164 for short is a recommendation which defines a numbering scheme and phone number formats. The Wikipedia entry is very helpful.

For coders, there are 2 important facts to be gleaned:

So, in e.g. ActiveRecord you can exploit fact #1 like this:

t.string "normalized_phone", :limit => 15

Fact #2 is harder to exploit, and this is what Phony is here for.

Model/Representation Aside

Btw, if you have customers who want to enter specific phone numbers (like “+34/123-(555)001!”), you could code it up like this in ActiveRecord:

Before saving, you could normalize it quickly if it is dirty, to see if it needs to be saved in the specific_phone attribute (if normalized != given_specific). This just off the top of my head.

def phone
  read_attribute(:specific_phone) || read_attribute(:normalized_phone)

Then, in the view, use e.g.:

= Phony.format(

Even better to use representers/view models, in which you just define a method:

def phone

Then, in the view it becomes:


I really like that last line.


At the time of this writing, we include 44 countries, and counting. See the README for a list.

Endnote 1

Q: Why are this dude’s libraries named after negative attributes?

A: No.

Endnote 2

If I’ve found out just one thing about phone numbers then it is this formula:

1 / (standardization + well-oiled-bureaucracy) = phone-number-structure-mess-quantifier

Switzerland has a well oiled bureaucracy, 1, but not a big drive for standardization, 0, = 1.

France does not have a well oiled bureaucracy, 0, but a big drive for standardization, 1, = 1.

For Italy, the result is around 1.825×10e7. Booo.

A special thank you goes to Belgium which uses 4xx as its mobile phone prefix, but has a region, Liège, which uses 4 as its land line prefix. Belgium, do you know what a bloody prefix code is? OTOH, this led me to rewrite Phony a second time, and all is much better.


So we’ve seen

  1. that Phony can normalize a phone number.
  2. that Phony can split a phone number into its constituent parts.
  3. that Phony can format a phone number for you.
  4. that it does all this very fast.
  5. what E164 is.
  6. what the lib status is.
  7. that some countries ARE better than others ;)

Hope you learnt something new!

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