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
— 517-203 5XXX6XXX8XXX9XXX · 3 holders which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-204 none assigned yet which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 LANSING MI
— 517-206 none assigned yet which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 JACKSON MI
— 517-207 not yet reported which blocks → TELNET WORLDWIDE, INC. 817J ADRIAN MI
— 517-211 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX MI
— 517-213 0–9 XXXall 10 · 5 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - MI 6120 CHARLOTTE MI
— 517-214 none assigned yet which blocks → OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 LANSING MI
— 517-217 not yet reported which blocks → TC3 TELECOM, INC. - MI 3459 CLINTON MI
— 517-223 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 FOWLERVL MI
— 517-226 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 LANSING MI
— 517-228 not yet reported which blocks → SPOK, INC. 6630 LANSING MI
— 517-229 not yet reported which blocks → SPOK, INC. 6630 LANSING MI
— 517-230 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LANSING MI
— 517-231 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 CHARLOTTE MI
— 517-232 not yet reported which blocks → SPOK, INC. 6630 LANSING MI
— 517-236 0–9 XXXall 10 · 4 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 DIMONDALE MI
— 517-237 0–9 XXXall 10 · 5 holders which blocks → ONVOY, LLCV - MI 543C LANSING MI
— 517-238 6XXX which blocks → FRONTIER NORTH, INC. - MI 0695 COLDWTR LK MI
— 517-241 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-242 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LANSING MI
— 517-243 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LANSING MI
— 517-244 5XXX6XXX7XXX which blocks → MICHIGAN BELL TEL CO 9323 MASON MI
— 517-248 not yet reported which blocks → MI
— 517-250 8XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 JACKSON MI
— 517-251 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 LANSING MI
— 517-252 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 ADDISON MI
— 517-254 not yet reported which blocks → FRONTIER COMMUNICATIONS OF MICHIGAN, INC. 4417 FRONTIER MI
— 517-255 not yet reported which blocks → AMERICAN MESSAGING SERVICES, LLC 9748 LANSING MI
— 517-256 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LANSING MI
— 517-260 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 ADRIAN MI
— 517-262 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 JACKSON MI
— 517-263 not yet reported which blocks → FRONTIER NORTH, INC. - MI 0695 ADRIAN MI
— 517-264 not yet reported which blocks → FRONTIER NORTH, INC. - MI 0695 ADRIAN MI
— 517-265 not yet reported which blocks → FRONTIER NORTH, INC. - MI 0695 ADRIAN MI
— 517-266 not yet reported which blocks → FRONTIER NORTH, INC. - MI 0695 ADRIAN MI
— 517-267 not yet reported which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-268 1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 HOLT MI
— 517-269 not yet reported which blocks → MI
— 517-270 5XXX7XXX8XXX9XXX which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 ADRIAN MI
— 517-272 8XXX which blocks → MICHIGAN BELL TEL CO 9323 LANSING MI
— 517-278 not yet reported which blocks → FRONTIER NORTH, INC. - MI 0695 COLDWATER MI
— 517-279 not yet reported which blocks → FRONTIER NORTH, INC. - MI 0695 COLDWATER MI
— 517-281 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LANSING MI
— 517-282 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LANSING MI
— 517-283 5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → FRONTIER NORTH, INC. - MI 0695 READING MI
— 517-285 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 LANSING MI
— 517-286 not yet reported which blocks → WALDRON TEL. CO. 0734 WALDRON MI
— 517-287 not yet reported which blocks → FRONTIER COMMUNICATIONS OF MICHIGAN, INC. 4417 NORTHADAMS MI
— 517-289 0–9 XXXall 10 · 3 holders which blocks → ONVOY, LLCV - MI 543C LANSING MI
— 517-290 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI 6003 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.