Area Code Guides

Learn what an area code means, what it can (and can’t) tell you about a phone number, and what changes when new codes are added—like overlays, splits, and 10-digit dialing.

How Area Codes Work

Learn the basics of NPAs, the NANP number structure, and why dialing rules change.

Read guide →

Overlay vs Split

Understand the difference between the two most common NPA relief methods and what they mean for 10-digit dialing.

Read guide →

About these guides

These articles focus on common questions people search for—what an area code means, why new codes are added, and what changes when an overlay or split is introduced. For the dataset behind this site, see Data Sources.

If you’re looking for a specific code, browse the area codes directory.