NumberResearchRecent prefix assignments
0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/24/2026
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 |
|---|---|---|---|---|---|---|
| — | 530-233 | not yet reported which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | ALTURAS | CA |
| — | 530-234 | 4XXX5XXX7XXX · 3 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | RAVENDALE | CA |
| — | 530-251 | none assigned yet which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | SUSANVILLE | CA |
| — | 530-252 | none assigned yet which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | SUSANVILLE | CA |
| — | 530-253 | 4XXX7XXX8XXX · 3 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | JANESVILLE | CA |
| — | 530-254 | 4XXX which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | JANESVILLE | CA |
| — | 530-257 | not yet reported which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | SUSANVILLE | CA |
| — | 530-258 | none assigned yet which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | CHESTER | CA |
| — | 530-259 | 6XXX8XXX · 2 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | CHESTER | CA |
| — | 530-279 | 8XXX which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | CEDARVILLE | CA |
| — | 530-281 | 7XXX which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | KEDDIE | CA |
| — | 530-284 | 2XXX3XXX5XXX · 3 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | GREENVILLE | CA |
| — | 530-294 | 7XXX which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | BIEBER | CA |
| — | 530-299 | 4XXX7XXX8XXX · 2 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | ADIN | CA |
| — | 530-335 | 1XXX which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | BURNEY | CA |
| — | 530-336 | 1XXX2XXX4XXX8XXX · 4 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | FALLRVRMLS | CA |
| — | 530-337 | 1XXX3XXX7XXX · 3 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | MONTGOYCRK | CA |
| — | 530-547 | 6XXX which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | MILLVILLE | CA |
| — | 530-549 | 6XXX8XXX · 2 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | MILLVILLE | CA |
| — | 530-595 | 1XXX4XXX · 2 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | MINERAL | CA |
| — | 530-597 | 7XXX which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | PAYNES CRK | CA |
| — | 530-825 | 2XXX7XXX · 2 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | EAGLE LAKE | CA |
| — | 530-827 | 1XXX7XXX · 2 holders which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | HERLONG | CA |
| — | 530-964 | 4XXX which blocks → | CITIZENS TELECOM CA. DBA FRONTIER COM OF CA | 2308 | MCCLOUD | CA |
Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/24/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.