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
2002-02-20 231-421 0–9 XXXall 10 · 5 holders which blocks → CHARTER IP ENABLED SERVICES, LLC 792K TRAVERSECY MI
2001-11-12 231-672 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - MI 770E MUSKEGON MI
2001-08-31 231-631 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 TRAVERSECY MI
2001-08-31 231-637 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J NORTHPORT MI
2001-08-31 231-764 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J FIFE LAKE MI
2001-08-27 231-647 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J CORAL MI
2001-08-27 231-822 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J BEULAH MI
2001-08-27 231-902 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J HART MI
2001-07-11 231-695 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J HOWARDCITY 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
2001-06-18 231-646 4XXX6XXX7XXX8XXX · 4 holders which blocks → FRONTIER NORTH, INC. - MI 0695 ELLSWORTH MI
2001-06-18 231-681 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → FRONTIER NORTH, INC. - MI 0695 FRUITPORT MI
2001-06-18 231-735 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 TRAVERSECY MI
2001-06-18 231-753 0–9 XXXall 10 · 8 holders which blocks → PAETEC ITEL, LLC 829J PETOSKEY MI
2001-06-18 231-790 0–9 XXXall 10 · 6 holders which blocks → PAETEC ITEL, LLC 829J FREESOIL 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
2001-06-18 231-930 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → ACD TELECOM, INC. - MI 3535 BEULAH MI
2001-06-18 231-936 0–9 XXXall 10 · 7 holders which blocks → PAETEC ITEL, LLC 829J SCOTTVILLE MI
2001-06-18 231-942 0–9 XXXall 10 · 6 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 CADILLAC MI
2001-05-18 231-674 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 GRANT MI
2001-05-18 231-791 2XXX3XXX4XXX5XXX7XXX · 4 holders which blocks → PAETEC ITEL, LLC 829J REED CITY MI
2001-05-18 231-803 1XXX3XXX4XXX5XXX6XXX7XXX · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 MORLEY MI
2001-05-18 231-923 0–9 XXXall 10 · 5 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 HART MI
2001-04-02 231-642 2XXX3XXX4XXX5XXX8XXX9XXX · 4 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 TRAVERSECY MI
2001-03-09 231-638 4XXX5XXX8XXX9XXX · 3 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 MUSKEGON MI
2001-02-21 231-670 8XXX which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 MUSKEGON MI
2001-02-05 231-468 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 CADILLAC MI
2001-02-05 231-580 0XXX4XXX5XXX7XXX8XXX · 3 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 BIG RAPIDS MI
2001-01-09 231-392 0XXX5XXX7XXX8XXX · 2 holders which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 TRAVERSECY MI
— 231-200 not yet reported which blocks → MI
— 231-204 not yet reported which blocks → SPOK, INC. 6630 FIFE LAKE MI
— 231-206 none assigned yet which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 MUSKEGON MI
— 231-211 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX MI
— 231-215 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 MUSKEGON MI
— 231-218 none assigned yet which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 TRAVERSECY MI
— 231-223 5XXX6XXX · 2 holders which blocks → ACE TEL. CO. OF MICHIGAN, INC. 0720 OLDMISSION MI
— 231-224 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → BANDWIDTH.COM CLEC, LLC - MI 991E FREMONT MI
— 231-228 not yet reported which blocks → BRIGHTSPEED OF MICHIGAN, LLC 0702 GLEN LAKE MI
— 231-229 not yet reported which blocks → BRIGHTSPEED OF MICHIGAN, LLC 0702 MOORESTOWN MI
— 231-231 not yet reported which blocks → MI
— 231-237 2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → MICHIGAN BELL TEL CO 9323 CHARLEVOIX MI
— 231-238 2XXX3XXX5XXX · 3 holders which blocks → MICHIGAN BELL TEL CO 9323 INDIAN RIV MI
— 231-242 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → MICHIGAN BELL TEL CO 9323 HARBOR SPG MI
— 231-248 not yet reported which blocks → MI
— 231-249 not yet reported which blocks → BANDWIDTH.COM CLEC, LLC - MI 991E CHEBOYGAN MI
— 231-250 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 BIG RAPIDS MI
— 231-255 not yet reported which blocks → SPOK, INC. 6630 ONEKAMA MI
— 231-256 1XXX3XXX4XXX5XXX6XXX · 5 holders which blocks → MICHIGAN BELL TEL CO 9323 LKLEELANAU 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.