Avoid these mistakes with phone numbers

Phone numbers are a complete mess. If you collect user phone numbers, you will encounter all sorts of local number formats that will make you scratch your head.

Turning them into one standard format is important to make them a searchable field in your database.

Here is a selection of different phone number formats people in different countries might use:

• 123-456-7890
• (234) 567-8901
• 0345 / 678 9012
• +456 789 0123
• 567-890-1234

How on earth will you turn those into the standard format?

The standard

E.123 by the International Telecommunication Union defines the international phone number format as this:

+12 345 678 901

Ideally, you would store all your phone numbers in this format, but without spaces in your database. To be safe, I would also store the raw string that the user has entered.

Avoid these mistakes

Mistake #1: Don't ask the user

If you can, collect the phone number in the correct format. A library like International Telephone Input can help you do this. Its phone number field looks like this:

Mistake #2: Save the number as an integer

If you just strip all the special characters and store the phone number as an integer, you are in deep trouble. 007 and 07 and 7 are not the same phone numbers, but you will store them simply as 7. Store phone numbers as strings.

Mistake #3: Don't use libraries

Google has open-sourced their libphonenumber and you should check it out! There is also a JavaScript-port called google-libphonenumber.

Mistake #4: Just prepend a country code

What if for a specific phone number using a library fails for you? Then use all the context info you have and figure out the country code the user could have implied. At this point it may be wise to feed that country info into one of the libraries and let them try to normalize the phone number again.

Final Thoughts

If you avoid these four mistakes, you should end up with nice and standard phone numbers in your database. With this format you can later look up records by phone number without worrying about special cases.

I've published a longer version of this at How to untangle phone numbers in the FactBranch blog. There I also write about philosophical aspects and fun facts like non-ASCII characters in phone numbers or that numbering plans can change over time.