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
2005-01-19 231-399 0–9 XXXall 10 · 6 holders which blocks → ACD TELECOM, INC. - MI 3535 FRANKFORT MI
2005-01-19 231-450 0–9 XXXall 10 · 4 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 HESPERIA MI
2005-01-19 231-515 0–9 XXXall 10 · 5 holders which blocks → ACD TELECOM, INC. - MI 3535 EVART MI
2005-01-19 231-678 7XXX8XXX · 2 holders which blocks → ACD TELECOM, INC. - MI 3535 BRETHREN MI
2005-01-19 231-774 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → ACD TELECOM, INC. - MI 3535 INTERLOCHN MI
2005-01-19 231-805 1XXX7XXX · 2 holders which blocks → ACD TELECOM, INC. - MI 3535 KALEVA MI
2005-01-19 231-994 0–9 XXXall 10 · 6 holders which blocks → ACD TELECOM, INC. - MI 3535 LKLEELANAU MI
2004-10-20 231-498 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 ELK RAPIDS MI
2004-10-05 231-404 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 STANWOOD MI
2004-08-30 231-233 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LUDINGTON MI
2004-08-24 231-445 3XXX4XXX5XXX6XXX7XXX9XXX · 5 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 CHEBOYGAN MI
2004-07-12 231-268 0XXX2XXX3XXX4XXX5XXX6XXX7XXX · 4 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 CHEBOYGAN MI
2004-04-28 231-239 2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LUDINGTON MI
2004-04-27 231-373 2XXX3XXX4XXX5XXX9XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 PETOSKEY MI
2004-03-25 231-209 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J SUTTONSBAY MI
2004-03-24 231-205 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J BRUTUS MI
2004-03-24 231-207 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J HONOR MI
2004-03-24 231-208 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J BOYNEFALLS MI
2004-03-24 231-217 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J BEAR LAKE MI
2004-03-24 231-219 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J MERRITT MI
2004-03-24 231-226 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J GLEN LAKE MI
2004-03-24 231-230 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J ELMIRA MI
2004-03-24 231-232 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J MOORESTOWN MI
2004-03-24 231-235 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J LEVERING MI
2004-03-24 231-236 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J LAKE CITY MI
2004-03-24 231-240 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J LAKE ANN MI
2004-03-24 231-243 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J ALANSON MI
2004-03-19 231-203 2XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 ALANSON MI
2004-03-05 231-201 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 CHIPPEWALK MI
2004-03-05 231-202 0XXX2XXX3XXX4XXX5XXX · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 MECOSTA MI
2004-01-09 231-459 0–9 XXXall 10 · 7 holders which blocks → PAETEC ITEL, LLC 829J BOYNE CITY MI
2003-07-29 231-394 2XXX7XXX · 2 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 MOORESTOWN MI
2003-07-09 231-340 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 ELMIRA MI
2003-07-09 231-350 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 BELLAIRE MI
2003-05-01 231-384 3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 KALKASKA MI
2003-05-01 231-388 4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LE ROY MI
2003-04-29 231-383 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 BEULAH MI
2003-03-25 231-220 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → 123.NET, LLC 2550 MUSKEGON MI
2003-02-27 231-366 0XXX1XXX3XXX5XXX6XXX7XXX9XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 FRUITPORT MI
2002-12-30 231-360 2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 TRAVERSECY MI
2002-12-10 231-330 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 PETOSKEY MI
2002-12-05 231-429 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 CADILLAC MI
2002-10-30 231-534 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 2 holders which blocks → AT&T - LOCAL 7421 TRAVERSECY MI
2002-10-24 231-679 6XXX7XXX8XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 BIG RAPIDS MI
2002-09-03 231-907 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 LUDINGTON MI
2002-08-30 231-432 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 NORTHPORT MI
2002-08-30 231-640 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 LAKE ANN MI
2002-08-30 231-651 1XXX2XXX3XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 BEULAH MI
2002-08-30 231-667 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 MARION MI
2002-08-30 231-676 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 BELLAIRE 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.