US Area codes
There are 326 area codes within the United States. You will find detailed information on each of them, on this page and browse all the area codes alphabetically:
Most area codes are related to a particular geographic location, but some of them, for example, toll-free codes, have more general meanings.
Phone number format
The phone number format is regulated by the North American Numbering Plan Administration (NANPA). Every phone number within the US follows the following pattern:
+1 201 345 7890 , where:
|+1||is the country code for the US|
|201||is the area code|
|345||is the prefix|
|7890||is the subscriber code|
While the area code gives you information on the geographic area used by a given phone number, the prefix might give a more precise location as well as the name of the operating company for that phone number.