Directory Numbers

In the United States and Canada, telephone numbers are typically 10 digits long and are structured as follows:

Area Code:

This is a three-digit number that represents a specific geographic region. Some area codes cover entire states or provinces, while others cover smaller regions, particularly in more densely populated areas.

Prefix (Central Office Code):

The prefix, or central office code, is the three-digit number that comes after the area code. It narrows down the location further and can sometimes identify a specific town or city, though mobile phone prefixes are not tied to specific geographic regions anymore.