We recently helped a global client determine what standards to use when listing phone numbers in print and on website.  The challenge was how to list U.S. versus international numbers.  Should we use parantheses? Hyphens? Plus signs?  We learned from extensive research that there are no clear, definitive standards.

Here is what we suggested to this client based on observation and the Chicago Manual of Style’s recommendation.

The Anatomy of a Phone Number

U.S. number:

Area Code – Phone Number

(for example: 617-739-3560)

International number:

+Country Code – Area Code – Phone Number

(for example: +86-10-5920-8207)

The international prefix symbol should be + (plus) and should precede the country code in the international number. It serves to remind the subscriber to dial the international prefix which differs from country to country and also serves to identify the number following as the international telephone number.

1) “+” indicates the option to enter a code if calling from another country
2) Hyphens create separations between country codes, area codes, and phone numbers

We felt that parentheses looked lovely in U.S. numbers but felt “old-school” when you saw them alongside international numbers.  Since it is not crucial to use the parentheses with U.S. numbers we opted to omit them in this international context.

What is your preference for phone number listing standards?