NumberResearchRecent prefix assignments
0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/20/2026
The Code holder is who opened each NPA-NXX prefix — not necessarily who holds the numbers. A prefix is 10,000 numbers, but under pooling its ten 1,000-number blocks are handed out individually, often to different carriers; the code holder may hold only one block, or none. The Thousands-blocks column shows how the ten blocks are really split — click which blocks → to see who holds each 1,000-number block and its last-4-digit range. Assignments are initial assignments; the current serving carrier may differ due to portability.
| Assigned | NPA-NXX | Thousands-blocks taken (last-4 opening) | Code holder | OCN | Rate center | State |
|---|---|---|---|---|---|---|
| 2010-07-12 | 831-296 | 0–9 XXXall 10 · 6 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SALINAS | CA |
| 2008-06-25 | 831-293 | 0–9 XXXall 10 · 9 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | CARMEL | CA |
| 2006-05-11 | 831-350 | 0XXX1XXX3XXX4XXX5XXX6XXX · 3 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | TRES PINOS | CA |
| 2005-06-03 | 831-920 | 0–9 XXXall 10 · 3 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | MONTEREY | CA |
| — | 831-223 | 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SOLEDAD | CA |
| — | 831-233 | 0–9 XXXall 10 · 4 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | MONTEREY | CA |
| — | 831-274 | 0XXX1XXX3XXX4XXX5XXX7XXX8XXX9XXX · 6 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | WATSONVL | CA |
| — | 831-299 | 8XXX which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | TRES PINOS | CA |
| — | 831-300 | 2XXX which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | BIG SUR | CA |
| — | 831-302 | 1XXX3XXX4XXX6XXX · 4 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SAN LUCAS | CA |
| — | 831-305 | 3XXX4XXX5XXX6XXX8XXX9XXX · 4 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | GONZALES | CA |
| — | 831-306 | 1XXX3XXX8XXX9XXX · 3 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | CHUALAR | CA |
| — | 831-307 | 1XXX which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | CASTROVL | CA |
| — | 831-359 | 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SANTA CRUZ | CA |
| — | 831-401 | 4XXX5XXX6XXX7XXX · 3 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | BEN LOMOND | CA |
| — | 831-525 | 0–9 XXXall 10 · 6 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | KING CITY | CA |
| — | 831-612 | 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | APTOS | CA |
| — | 831-621 | 2XXX5XXX7XXX · 3 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SANTA CRUZ | CA |
| — | 831-652 | 0–9 XXXall 10 · 8 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | CARMEL VLY | CA |
| — | 831-664 | 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | HOLLISTER | CA |
| — | 831-665 | 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 5 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | HOLLISTER | CA |
| — | 831-709 | 0XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | BEN LOMOND | CA |
| — | 831-732 | 1XXX3XXX4XXX5XXX7XXX8XXX9XXX · 4 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SAN ARDO | CA |
| — | 831-741 | 0–9 XXXall 10 · 6 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | CASTROVL | CA |
| — | 831-778 | 1XXX2XXX3XXX4XXX9XXX · 5 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SAN LUCAS | CA |
| — | 831-921 | 0XXX1XXX2XXX3XXX · 3 holders which blocks → | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | TRES PINOS | CA |
Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.