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
LEVEL 3 COMMUNICATIONS, LLC - MT 27
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
2023-02-22 406-512 0XXX1XXX2XXX8XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 BOULDER MT
2023-02-17 406-507 0XXX1XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 WHITEFISH MT
2021-02-12 406-504 2XXX which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 FAIRFIELD MT
2018-11-27 406-902 1XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 SHERIDAN MT
2017-09-29 406-900 0XXX1XXX2XXX4XXX7XXX8XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 ENNIS MT
2012-02-03 406-508 0–9 XXXall 10 · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 FRENCHTOWN MT
2005-02-16 406-630 0–9 XXXall 10 · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 SIDNEY MT
2005-01-07 406-988 0XXX4XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 DILLON MT
2004-10-26 406-924 0–9 XXXall 10 · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 BELGRADE MT
2003-05-06 406-213 1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 COLSTRIP MT
2003-01-23 406-299 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 BUTTE MT
2003-01-09 406-943 1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 SIDNEY MT
2003-01-09 406-944 1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 MILES CITY MT
2003-01-09 406-946 1XXX2XXX3XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 LIVINGSTON MT
2003-01-09 406-948 1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 GLENDIVE MT
2003-01-09 406-960 none assigned yet which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 DILLON MT
2003-01-09 406-966 1XXX2XXX3XXX5XXX6XXX7XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 SHELBY MT
2002-06-19 406-545 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 BILLINGS MT
2002-06-19 406-551 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 BOZEMAN MT
2002-06-19 406-552 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 MISSOULA MT
2002-06-19 406-564 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 GREATFALLS MT
2002-06-19 406-565 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 BUTTE MT
— 406-203 2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 MISSOULA MT
— 406-204 1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 HELENA MT
— 406-205 9XXX which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 GREATFALLS MT
— 406-206 not yet reported which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 BILLINGS MT
— 406-530 0–9 XXXall 10 · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MT 9415 LAUREL 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.