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
— 406-446 6XXX7XXX8XXX which blocks → QWEST CORPORATION 9636 RED LODGE MT
— 406-447 0XXX which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-449 not yet reported which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-452 not yet reported which blocks → QWEST CORPORATION 9636 GREATFALLS MT
— 406-453 not yet reported which blocks → QWEST CORPORATION 9636 GREATFALLS MT
— 406-454 not yet reported which blocks → QWEST CORPORATION 9636 GREATFALLS MT
— 406-455 none assigned yet which blocks → QWEST CORPORATION 9636 GREATFALLS MT
— 406-457 6XXX which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-458 none assigned yet which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-468 1XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → QWEST CORPORATION 9636 CASCADE MT
— 406-475 0XXX1XXX2XXX4XXX5XXX6XXX7XXX · 2 holders which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-476 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → QWEST CORPORATION 9636 DUTTON MT
— 406-482 0XXX5XXX which blocks → QWEST CORPORATION 9636 SIDNEY MT
— 406-494 not yet reported which blocks → QWEST CORPORATION 9636 BUTTE MT
— 406-495 none assigned yet which blocks → QWEST CORPORATION 9636 HELENA MT
— 406-496 7XXX which blocks → QWEST CORPORATION 9636 BUTTE MT
— 406-497 0XXX which blocks → QWEST CORPORATION 9636 BUTTE MT
— 406-522 not yet reported which blocks → QWEST CORPORATION 9636 BOZEMAN MT
— 406-523 not yet reported which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-533 4XXX5XXX8XXX9XXX · 2 holders which blocks → QWEST CORPORATION 9636 BUTTE MT
— 406-538 none assigned yet which blocks → QWEST CORPORATION 9636 LEWISTOWN MT
— 406-542 not yet reported which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-543 not yet reported which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-548 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → QWEST CORPORATION 9636 BOZEMAN MT
— 406-549 not yet reported which blocks → QWEST CORPORATION 9636 MISSOULA MT
— 406-556 not yet reported which blocks → QWEST CORPORATION 9636 BOZEMAN MT
— 406-563 0XXX which blocks → QWEST CORPORATION 9636 ANACONDA MT
— 406-574 0XXX2XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → QWEST CORPORATION 9636 SILVERTIP MT
— 406-578 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 WILSALL MT
— 406-582 not yet reported which blocks → QWEST CORPORATION 9636 BOZEMAN MT
— 406-585 not yet reported which blocks → QWEST CORPORATION 9636 BOZEMAN MT
— 406-586 not yet reported which blocks → QWEST CORPORATION 9636 BOZEMAN MT
— 406-587 not yet reported which blocks → QWEST CORPORATION 9636 BOZEMAN MT
— 406-626 3XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → QWEST CORPORATION 9636 FRENCHTOWN MT
— 406-628 0XXX which blocks → QWEST CORPORATION 9636 LAUREL MT
— 406-633 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 LAUREL MT
— 406-637 3XXX4XXX6XXX7XXX8XXX · 3 holders which blocks → QWEST CORPORATION 9636 TERRY MT
— 406-642 0XXX4XXX5XXX7XXX8XXX · 2 holders which blocks → QWEST CORPORATION 9636 VICTOR MT
— 406-646 2XXX3XXX6XXX8XXX · 3 holders which blocks → QWEST CORPORATION 9636 WYELLOWSTN MT
— 406-651 7XXX which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-652 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-655 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-656 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-657 not yet reported which blocks → QWEST CORPORATION 9636 BILLINGS MT
— 406-659 5XXX6XXX7XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 NO PARKMAN MT
— 406-662 0XXX1XXX2XXX4XXX6XXX7XXX8XXX · 5 holders which blocks → QWEST CORPORATION 9636 BRIDGER MT
— 406-665 0XXX which blocks → QWEST CORPORATION 9636 HARDIN MT
— 406-668 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX · 5 holders which blocks → QWEST CORPORATION 9636 FROMBERG MT
— 406-683 not yet reported which blocks → QWEST CORPORATION 9636 DILLON MT
— 406-686 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → QWEST CORPORATION 9636 CLYDE PARK 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.