Area Codes Running Out of Numbers

NANPA monitors number utilization across all area codes and triggers a relief process when an area code's available numbers fall below a threshold — typically when 10% or fewer numbers remain unassigned.

Overlays are the most common modern relief method: a new area code is added to the same geographic territory, and 10-digit dialing becomes required for all local calls. No existing numbers change.

Geographic splits divide the territory, with part of the region moving to a new code. Businesses and residents in the relocated portion must update their number — a disruptive and increasingly rare approach.

From the time relief planning begins to when a new code goes into service typically takes 18–24 months.