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 |
|---|---|---|---|---|---|---|
| — | 559-332 | 0XXX3XXX4XXX5XXX6XXX8XXX9XXX · 5 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | SQUAW VLY | CA |
| — | 559-335 | 0XXX1XXX3XXX4XXX5XXX8XXX9XXX · 5 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | GRANTGROVE | CA |
| — | 559-336 | 0XXX1XXX4XXX5XXX6XXX8XXX · 4 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | MIRANTPHST | CA |
| — | 559-337 | 1XXX3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | BADGER | CA |
| — | 559-338 | 1XXX3XXX4XXX5XXX6XXX7XXX8XXX which blocks → | FRONTIER CALIFORNIA INC. | 2319 | DUNLAP | CA |
| — | 559-562 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LINDSAY | CA |
| — | 559-568 | 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | LINDSAY | CA |
| — | 559-592 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 4420 | EXETER | CA |
| — | 559-594 | 0XXX1XXX2XXX3XXX7XXX8XXX · 5 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | EXETER | CA |
| — | 559-597 | 0XXX1XXX4XXX5XXX6XXX8XXX · 4 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | LEMON COVE | CA |
| — | 559-637 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | REEDLEY | CA |
| — | 559-638 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 2319 | REEDLEY | CA |
| — | 559-643 | 1XXX2XXX3XXX4XXX5XXX6XXX7XXX9XXX · 3 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | REEDLEY | CA |
| — | 559-693 | 5XXX6XXX which blocks → | FRONTIER CALIFORNIA INC. | 4420 | SANJOAQUIN | CA |
| — | 559-698 | 3XXX4XXX6XXX8XXX · 2 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | SANJOAQUIN | CA |
| — | 559-787 | 0XXX1XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | TIVYVALLEY | CA |
| — | 559-829 | 2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | SANJOAQUIN | CA |
| — | 559-834 | 7XXX8XXX · 2 holders which blocks → | FRONTIER CALIFORNIA INC. | 2319 | FOWLER | CA |
| — | 559-875 | not yet reported which blocks → | FRONTIER CALIFORNIA INC. | 4420 | SANGER | CA |
| — | 559-876 | 0XXX4XXX5XXX7XXX8XXX9XXX · 4 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | SANGER | CA |
| — | 559-949 | 0XXX1XXX2XXX3XXX4XXX7XXX · 3 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | ALPAUGH | CA |
| — | 559-992 | 0XXX6XXX · 2 holders which blocks → | FRONTIER CALIFORNIA INC. | 4420 | CORCORAN | 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.