Country code in telephone numbers

Question:

Does the 1 need to be included when writing out 800 and 900 telephone numbers? For instance, which is the correct format: 1-800-555-5555 or 800-555-5555?

Answer:

The 1 in 800 and 900 numbers is the country code for North America. Therefore, if you are addressing a uniquely North American readership, there is no need to include the 1. If your documents are going to be read on other continents, you need to include the country code followed by a hyphen (e.g. 1-800-555-5555).