NumberResearch Membership · Data 09/19/2026

Recent prefix assignments

1 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, last 30 days — NPA 517
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 1
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
— 517-474 6XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 JACKSON MI
— 517-480 1XXX2XXX3XXX4XXX5XXX7XXX8XXX9XXX · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 STOCKBDG MI
— 517-481 0XXX2XXX3XXX4XXX5XXX6XXX · 3 holders which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-482 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-483 2XXX3XXX · 2 holders which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-484 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-485 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-486 1XXX which blocks → FRONTIER NORTH, INC. - MI 0695 BLISSFIELD MI
— 517-487 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-492 5XXX6XXX7XXX8XXX · 3 holders which blocks → ONVOY, LLCV - MI 543C LANSING MI
— 517-494 7XXX8XXX9XXX · 2 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 ALBION MI
— 517-499 0XXX1XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 JACKSON MI
— 517-502 not yet reported which blocks → TC3 TELECOM, INC. - MI 3459 HUDSON MI
— 517-504 not yet reported which blocks → TC3 TELECOM, INC. - MI 3459 MORENCI MI
— 517-505 not yet reported which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 LANSING MI
— 517-507 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 LANSING MI
— 517-511 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX MI
— 517-512 1XXX2XXX6XXX7XXX8XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LANSING MI
— 517-513 0XXX3XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 JACKSON MI
— 517-517 not yet reported which blocks → MI
— 517-521 0XXX7XXX8XXX9XXX · 3 holders which blocks → FRONTIER MIDSTATES, INC. - MI 0681 WEBBERVL MI
— 517-522 0XXX1XXX2XXX7XXX9XXX · 5 holders which blocks → FRONTIER NORTH, INC. - MI 0695 GRASS LAKE MI
— 517-523 not yet reported which blocks → FRONTIER COMMUNICATIONS OF MICHIGAN, INC. 4417 OSSEO MI
— 517-524 not yet reported which blocks → FRONTIER COMMUNICATIONS OF MICHIGAN, INC. 4417 CONCORD MI
— 517-525 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 MASON MI
— 517-526 6XXX7XXX9XXX · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 PORTLAND MI
— 517-529 2XXX6XXX7XXX · 3 holders which blocks → MICHIGAN BELL TEL CO 9323 CLARKLAKE MI
— 517-531 0XXX2XXX6XXX9XXX · 4 holders which blocks → FRONTIER MIDSTATES, INC. - MI 0681 PARMA MI
— 517-534 not yet reported which blocks → SPOK, INC. 6630 JACKSON MI
— 517-536 1XXX2XXX3XXX5XXX6XXX7XXX9XXX · 5 holders which blocks → MICHIGAN BELL TEL CO 9323 NAPOLEON MI
— 517-540 5XXX which blocks → MICHIGAN BELL TEL CO 9323 HOWELL MI
— 517-541 4XXX6XXX7XXX · 3 holders which blocks → MICHIGAN BELL TEL CO 9323 CHARLOTTE MI
— 517-542 not yet reported which blocks → BRIGHTSPEED OF CENTRAL MICHIGAN, INC 0671 LITCHFIELD MI
— 517-543 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 CHARLOTTE MI
— 517-545 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 HOWELL MI
— 517-546 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 HOWELL MI
— 517-547 0XXX1XXX2XXX · 3 holders which blocks → FRONTIER MIDSTATES, INC. - MI 0681 ADDISON MI
— 517-548 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 HOWELL MI
— 517-549 not yet reported which blocks → BRIGHTSPEED OF CENTRAL MICHIGAN, INC 0671 MOSHERVL MI
— 517-552 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 HOWELL MI
— 517-555 not yet reported which blocks → MULTIPLE OCN LISTING MULT DIR ASST MI
— 517-563 not yet reported which blocks → FRONTIER COMMUNICATIONS OF MICHIGAN, INC. 4417 HANOVER MI
— 517-564 not yet reported which blocks → SPOK, INC. 6630 ADRIAN MI
— 517-565 0XXX2XXX4XXX5XXX6XXX7XXX9XXX · 4 holders which blocks → FRONTIER MIDSTATES, INC. - MI 0681 FITCHBURG MI
— 517-566 0XXX1XXX2XXX3XXX4XXX6XXX9XXX · 4 holders which blocks → BRIGHTSPEED OF CENTRAL MICHIGAN, INC 0671 SUNFIELD MI
— 517-567 not yet reported which blocks → FRONTIER COMMUNICATIONS OF MICHIGAN, INC. 4417 RANSOM MI
— 517-568 0XXX1XXX2XXX8XXX9XXX · 4 holders which blocks → FRONTIER MIDSTATES, INC. - MI 0681 HOMER MI
— 517-569 0XXX1XXX4XXX5XXX6XXX7XXX · 4 holders which blocks → FRONTIER MIDSTATES, INC. - MI 0681 RIVES JCT MI
— 517-571 not yet reported which blocks → SPOK, INC. 6630 HOWELL MI
— 517-575 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → MICHIGAN BELL TEL CO 9323 LANSING 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.