NumberResearchNPA Prefix-Assignment Utilization
Professional access · version 2026-09-18 (latest) · 233,683 rows · Members — internal use
Per-NPA count of assigned prefixes and approximate prefix-assignment utilization (assigned ÷ ~792 assignable NXX).
Schema3 columns
| Column | Description |
|---|---|
| npa | area code |
| assigned_prefixes | count of assigned NXX |
| approx_utilization_pct | assigned ÷ ~792 assignable NXX |
Known limitations
This is prefix-assignment utilization, NOT the share of individual phone numbers in use. Thousands-block pooling and number-level utilization are separate concepts. Counts can exceed the ~792 denominator because the CO code file includes some service/special codes.
Machine-readable catalog: /datasets.json · /data-sources.json. Cited versions never change — a version URL always resolves to the exact release. See methodology and licensing.