NumberResearch Membership · Data 09/19/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/19/2026

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 231
NEW CINGULAR WIRELESS PCS, LLC - IL 72
MICHIGAN BELL TEL CO 72
FRONTIER NORTH, INC. - MI 52
ONVOY, LLCV - MI 49
TELNET WORLDWIDE, INC. 43
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
2021-06-25 231-297 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → ONVOY, LLCV - MI 543C KINGSLEY MI
2021-06-25 231-367 1XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → ONVOY, LLCV - MI 543C WOLVERINE MI
2021-06-15 231-294 3XXX4XXX5XXX7XXX8XXX9XXX · 3 holders which blocks → ONVOY, LLCV - MI 543C FIFE LAKE MI
2021-06-15 231-364 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → ONVOY, LLCV - MI 543C NORTHPORT MI
2021-06-15 231-374 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → ONVOY, LLCV - MI 543C SHELBY MI
2021-05-25 231-324 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - MI 770E HARBOR SPG MI
2021-05-21 231-270 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → ONVOY, LLCV - MI 543C BOYNE CITY MI
2021-05-19 231-321 0XXX1XXX3XXX4XXX5XXX7XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 ELMIRA MI
2021-05-19 231-431 0XXX1XXX3XXX4XXX5XXX7XXX · 3 holders which blocks → ONVOY, LLCV - MI 543C CLAM RIVER MI
2021-05-14 231-293 0–9 XXXall 10 · 4 holders which blocks → HD CARRIER LLC 321J FRANKFORT MI
2021-05-13 231-296 0XXX1XXX2XXX4XXX5XXX6XXX7XXX9XXX · 7 holders which blocks → CHARTER IP ENABLED SERVICES, LLC 792K FREMONT MI
2021-05-13 231-298 0XXX2XXX4XXX7XXX8XXX9XXX · 4 holders which blocks → CHARTER IP ENABLED SERVICES, LLC 792K IRONS MI
2021-05-13 231-381 0XXX1XXX3XXX7XXX · 4 holders which blocks → CHARTER IP ENABLED SERVICES, LLC 792K WHITECLOUD MI
2021-05-13 231-449 0XXX1XXX3XXX4XXX5XXX6XXX9XXX · 4 holders which blocks → CHARTER IP ENABLED SERVICES, LLC 792K BALDWIN MI
2021-03-24 231-786 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → FRACTEL, LLC 965H TRAVERSECY MI
2021-03-01 231-284 0–9 XXXall 10 · 7 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 MANISTEE MI
2021-01-08 231-443 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → ONVOY, LLCV - MI 543C HONOR MI
2021-01-08 231-455 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX · 2 holders which blocks → ONVOY, LLCV - MI 543C PENTWATER MI
2020-12-02 231-567 0–9 XXXall 10 · 3 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - MI 770E MUSKEGON MI
2020-11-09 231-283 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 3 holders which blocks → ONVOY, LLCV - MI 543C MUSKEGON MI
2020-11-03 231-281 0–9 XXXall 10 · 5 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CADILLAC MI
2020-10-26 231-273 0–9 XXXall 10 · 2 holders which blocks → ONVOY, LLCV - MI 543C EASTPORT MI
2020-10-26 231-278 0–9 XXXall 10 · 4 holders which blocks → ONVOY SPECTRUM, LLC 624H HESPERIA MI
2020-10-26 231-304 0XXX1XXX2XXX3XXX4XXX5XXX8XXX9XXX · 4 holders which blocks → ONVOY, LLCV - MI 543C BRUTUS MI
2020-02-19 231-688 1XXX6XXX8XXX · 3 holders which blocks → FRACTEL, LLC 965H MERRITT MI
2020-02-19 231-977 0XXX2XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → FRACTEL, LLC 965H MACKINAWCY MI
2020-01-09 231-285 0XXX1XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 CADILLAC MI
2019-12-20 231-279 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 BIG RAPIDS MI
2019-12-19 231-600 0–9 XXXall 10 · 6 holders which blocks → FRACTEL, LLC 965H TRAVERSECY MI
2019-10-24 231-254 0XXX1XXX2XXX3XXX4XXX5XXX7XXX9XXX · 5 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 PETOSKEY MI
2019-10-10 231-400 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 3 holders which blocks → ONVOY, LLCV - MI 543C ALANSON MI
2019-10-10 231-500 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → ONVOY, LLCV - MI 543C WHITEHALL MI
2019-08-08 231-272 0–9 XXXall 10 · 2 holders which blocks → ONVOY, LLCV - MI 543C KINGSLEY MI
2019-05-13 231-900 0–9 XXXall 10 · 6 holders which blocks → FRACTEL, LLC 965H MUSKEGON MI
2019-04-19 231-763 0XXX8XXX · 2 holders which blocks → CHARTER IP ENABLED SERVICES, LLC 792K AMBLE MI
2019-04-09 231-531 0–9 XXXall 10 · 4 holders which blocks → METROPCS, INC. 5562 MUSKEGON MI
2019-02-27 231-257 0XXX4XXX · 2 holders which blocks → PENINSULA FIBER NETWORK, LLC - MI 116F LAKE CITY MI
2018-12-31 231-261 0–9 XXXall 10 · 2 holders which blocks → PENINSULA FIBER NETWORK, LLC - MI 116F LUDINGTON MI
2018-11-08 231-253 0–9 XXXall 10 · 5 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 CADILLAC MI
2018-09-28 231-247 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → BANDWIDTH.COM CLEC, LLC - MI 991E WILLIAMSBG MI
2018-09-25 231-310 0–9 XXXall 10 · 2 holders which blocks → ONVOY, LLCV - MI 543C FALMOUTH MI
2018-07-19 231-289 0–9 XXXall 10 · 5 holders which blocks → BANDWIDTH.COM CLEC, LLC - MI 991E CHARLEVOIX MI
2017-10-09 231-666 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLCV - MI 543C MUSKEGON MI
2017-10-02 231-800 0XXX2XXX5XXX7XXX8XXX · 4 holders which blocks → ONVOY, LLCV - MI 543C LUTHER MI
2017-09-07 231-300 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 2 holders which blocks → ONVOY, LLCV - MI 543C ALDEN MI
2017-08-09 231-939 0–9 XXXall 10 · 4 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 PETOSKEY MI
2017-05-17 231-493 0–9 XXXall 10 · 4 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 TRAVERSECY MI
2017-04-20 231-581 none assigned yet which blocks → CHARTER IP ENABLED SERVICES, LLC 792K ALBA MI
2017-03-03 231-260 0–9 XXXall 10 · 3 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 MUSKEGON MI
2016-09-23 231-545 0XXX1XXX2XXX3XXX4XXX5XXX6XXX9XXX · 5 holders which blocks → CHARTER IP ENABLED SERVICES, LLC 792K BOYNEFALLS MI

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.