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
LEVEL 3 COMMUNICATIONS, LLC - MI 19
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
2019-12-20 231-279 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 BIG RAPIDS MI
2004-10-20 231-498 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 ELK RAPIDS MI
2003-02-27 231-366 0XXX1XXX3XXX5XXX6XXX7XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 FRUITPORT MI
2002-08-19 231-622 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 PETOSKEY MI
2002-08-19 231-680 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 REED CITY MI
2002-05-23 231-480 1XXX2XXX3XXX4XXX6XXX7XXX8XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 LUDINGTON MI
2002-05-14 231-577 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 CADILLAC MI
2002-04-29 231-668 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 TRAVERSECY MI
2002-04-29 231-903 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 MUSKEGON MI
2002-04-04 231-222 1XXX2XXX3XXX4XXX5XXX6XXX7XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 EASTJORDAN MI
2002-04-04 231-225 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 FREMONT MI
2002-04-04 231-333 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 CHEBOYGAN MI
2001-07-09 231-683 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 MUSKEGON MI
2001-06-18 231-518 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 7 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 KALKASKA MI
2001-06-18 231-844 0–9 XXXall 10 · 9 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 INDIAN RIV MI
2001-06-18 231-916 1XXX2XXX3XXX4XXX5XXX6XXX7XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 MANCELONA MI
2001-05-18 231-674 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 GRANT MI
2001-05-18 231-803 1XXX3XXX4XXX5XXX6XXX7XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 MORLEY MI
— 231-648 2XXX3XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 HOWARDCITY 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.