NumberResearch Membership · Data 09/20/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/20/2026

Full prefixes (NXX) Thousands-blocks (1,000-number pools)

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.

Most active assignees, all time — NPA 406
QWEST CORPORATION 132
New assignments by month Sep 2026 Aug 2026 Jul 2026 Jun 2026 May 2026 Apr 2026 Mar 2026 Feb 2026 Jan 2026 Dec 2025 Nov 2025 Oct 2025
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Recent NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
2015-05-12 406-413 0–9 XXXall 10 · 6 holders which blocks → QWEST CORPORATION 9636 BILLINGS MT
2011-12-07 406-414 0–9 XXXall 10 · 3 holders which blocks → QWEST CORPORATION 9636 BOZEMAN MT
— 406-222 not yet reported which blocks → QWEST CORPORATION 9636 LIVINGSTON MT
— 406-225 0XXX1XXX2XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 BOULDER MT
— 406-226 0XXX1XXX2XXX3XXX6XXX7XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 EGLACIERPK MT
— 406-227 not yet reported which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-232 not yet reported which blocks → QWEST CORPORATION 9636 MILES CITY MT
— 406-233 0XXX1XXX6XXX8XXX9XXX · 3 holders which blocks → QWEST CORPORATION 9636 MILES CITY MT
— 406-235 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → QWEST CORPORATION 9636 WOLF CREEK MT
— 406-237 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-238 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-243 not yet reported which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-245 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-247 0XXX9XXX · 2 holders which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-248 0XXX which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-251 not yet reported which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-252 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-254 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-255 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-256 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-258 0XXX1XXX7XXX8XXX · 3 holders which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-259 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-262 0XXX6XXX7XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 HAVRE MT
— 406-265 not yet reported which blocks → QWEST CORPORATION 9636 HAVRE MT
— 406-266 0XXX1XXX6XXX7XXX · 3 holders which blocks → QWEST CORPORATION 9636 TOWNSEND MT
— 406-268 4XXX5XXX · 2 holders which blocks → QWEST CORPORATION 9636 GREATFALLS MT
— 406-273 1XXX8XXX which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-278 1XXX2XXX6XXX8XXX · 3 holders which blocks → QWEST CORPORATION 9636 CONRAD MT
— 406-282 0XXX1XXX2XXX3XXX4XXX5XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 MANHATTAN MT
— 406-284 0XXX1XXX2XXX5XXX7XXX8XXX · 3 holders which blocks → QWEST CORPORATION 9636 MANHATTAN MT
— 406-285 1XXX2XXX7XXX8XXX · 3 holders which blocks → QWEST CORPORATION 9636 THREEFORKS MT
— 406-287 0XXX1XXX4XXX6XXX8XXX · 3 holders which blocks → QWEST CORPORATION 9636 WHITEHALL MT
— 406-322 2XXX3XXX7XXX · 2 holders which blocks → QWEST CORPORATION 9636 COLUMBUS MT
— 406-324 0XXX7XXX8XXX9XXX · 3 holders which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-327 not yet reported which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-329 not yet reported which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-333 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX · 7 holders which blocks → QWEST CORPORATION 9636 LIVINGSTON MT
— 406-356 0XXX1XXX5XXX6XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 FORSYTH MT
— 406-359 0XXX1XXX5XXX6XXX8XXX9XXX · 6 holders which blocks → QWEST CORPORATION 9636 GLENDIVE MT
— 406-363 none assigned yet which blocks → QWEST CORPORATION 9636 HAMILTON MT
— 406-365 0XXX1XXX · 2 holders which blocks → QWEST CORPORATION 9636 GLENDIVE MT
— 406-373 2XXX4XXX8XXX · 2 holders which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-375 1XXX3XXX5XXX · 3 holders which blocks → QWEST CORPORATION 9636 HAMILTON MT
— 406-388 not yet reported which blocks → QWEST CORPORATION 9636 BELGRADE MT
— 406-434 1XXX4XXX6XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 SHELBY MT
— 406-441 not yet reported which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-442 not yet reported which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-443 not yet reported which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-444 not yet reported which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-445 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → QWEST CORPORATION 9636 RED LODGE MT

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.