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 331
T-MOBILE USA, INC. 42
ONVOY, LLC 39
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 33
NEW CINGULAR WIRELESS PCS, LLC - IL 26
FRACTEL, LLC 18
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
2022-02-17 331-466 0–9 XXXall 10 · 3 holders which blocks → TON80 COMMUNICATIONS, LLC 516J GLEN ELLYN IL
2022-02-17 331-688 0–9 XXXall 10 · 3 holders which blocks → TON80 COMMUNICATIONS, LLC 516J NAPERVILLE IL
2022-02-17 331-746 0XXX2XXX7XXX · 3 holders which blocks → TON80 COMMUNICATIONS, LLC 516J KANEVILLE IL
2022-01-13 331-866 0–9 XXXall 10 · 4 holders which blocks → TON80 COMMUNICATIONS, LLC 516J WHEATON IL
2022-01-07 331-837 0XXX1XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → TON80 COMMUNICATIONS, LLC 516J W CHICAGO IL
2021-12-29 331-280 0–9 XXXall 10 · 3 holders which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 DOWNERSGRV IL
2021-12-10 331-282 0–9 XXXall 10 · 6 holders which blocks → ONVOY, LLC 224C HINSDALE IL
2021-10-27 331-758 0–9 XXXall 10 · 5 holders which blocks → FRACTEL, LLC 965H AURORA IL
2021-10-15 331-279 0–9 XXXall 10 · 4 holders which blocks → PAETEC ITEL, LLC 829J ELMHURST IL
2021-08-13 331-278 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 AURORA IL
2021-08-06 331-277 0–9 XXXall 10 · 3 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 LOMBARD IL
2021-08-03 331-274 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 AURORA IL
2021-08-03 331-275 2XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 BARTLETT IL
2021-07-20 331-270 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLC 224C AURORA IL
2021-07-15 331-272 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLC 224C ST CHARLES IL
2021-06-09 331-273 0–9 XXXall 10 · 3 holders which blocks → ONVOY, LLC 224C LEMONT IL
2021-06-02 331-334 0–9 XXXall 10 · 5 holders which blocks → ONVOY, LLC 224C BATAVIA IL
2021-05-14 331-269 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 AURORA IL
2021-03-30 331-341 0–9 XXXall 10 · 4 holders which blocks → ONVOY, LLC 224C PLANO IL
2021-03-30 331-850 1XXX3XXX5XXX8XXX9XXX · 5 holders which blocks → ONVOY, LLC 224C BIG ROCK IL
2021-01-25 331-388 0XXX1XXX3XXX4XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → FRACTEL, LLC 965H SUGARGROVE IL
2021-01-25 331-788 0XXX1XXX3XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → FRACTEL, LLC 965H GENEVA IL
2021-01-22 331-399 0–9 XXXall 10 · 5 holders which blocks → FRACTEL, LLC 965H DOWNERSGRV IL
2021-01-14 331-268 0XXX1XXX2XXX3XXX4XXX9XXX · 4 holders which blocks → T-MOBILE USA, INC. 6529 SUGARGROVE IL
2021-01-04 331-299 0–9 XXXall 10 · 3 holders which blocks → FRACTEL, LLC 965H HINSDALE IL
2021-01-04 331-500 0XXX1XXX2XXX3XXX4XXX5XXX8XXX9XXX · 5 holders which blocks → FRACTEL, LLC 965H GENEVA IL
2020-12-22 331-899 0–9 XXXall 10 · 4 holders which blocks → FRACTEL, LLC 965H LOMBARD IL
2020-11-18 331-345 0–9 XXXall 10 · 5 holders which blocks → FRACTEL, LLC 965H NAPERVILLE IL
2020-10-21 331-271 0–9 XXXall 10 · 5 holders which blocks → ONVOY, LLC 224C HINSDALE IL
2020-09-18 331-267 0–9 XXXall 10 · 3 holders which blocks → VONAGE AMERICA LLC 197D LOMBARD IL
2020-07-14 331-867 0XXX1XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → FRACTEL, LLC 965H YORKVILLE IL
2020-07-14 331-946 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → FRACTEL, LLC 965H GLEN ELLYN IL
2020-04-10 331-266 0–9 XXXall 10 · 6 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 ST CHARLES IL
2020-03-06 331-264 0–9 XXXall 10 · 4 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - IL 6115 HINSDALE IL
2020-01-17 331-257 0–9 XXXall 10 · 5 holders which blocks → NEW CINGULAR WIRELESS PCS, LLC - IL 6534 AURORA IL
2019-10-11 331-336 0–9 XXXall 10 · 3 holders which blocks → FRACTEL, LLC 965H AURORA IL
2019-10-11 331-348 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → FRACTEL, LLC 965H ELBURN IL
2019-10-11 331-732 0–9 XXXall 10 · 2 holders which blocks → FRACTEL, LLC 965H GENEVA IL
2019-10-10 331-356 0–9 XXXall 10 · 4 holders which blocks → FRACTEL, LLC 965H BARTLETT IL
2019-08-08 331-400 0–9 XXXall 10 · 6 holders which blocks → FRACTEL, LLC 965H OSWEGO IL
2019-08-08 331-529 0–9 XXXall 10 · 5 holders which blocks → FRACTEL, LLC 965H NAPERVILLE IL
2019-08-08 331-600 0–9 XXXall 10 · 6 holders which blocks → FRACTEL, LLC 965H WHEATON IL
2019-08-08 331-900 0–9 XXXall 10 · 6 holders which blocks → FRACTEL, LLC 965H ELMHURST IL
2019-06-20 331-261 0XXX1XXX3XXX4XXX5XXX6XXX9XXX · 5 holders which blocks → T-MOBILE USA, INC. 6529 LEMONT IL
2019-02-25 331-260 0–9 XXXall 10 · 5 holders which blocks → TELEPORT COMMUNICATIONS AMERICA, LLC - IL 7136 DOWNERSGRV IL
2018-12-05 331-249 0–9 XXXall 10 · 5 holders which blocks → ONVOY, LLC 224C NAPERVILLE IL
2018-11-21 331-247 0–9 XXXall 10 · 2 holders which blocks → VONAGE AMERICA LLC 197D NAPERVILLE IL
2018-10-19 331-242 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 LOMBARD IL
2018-10-19 331-243 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 LOMBARD IL
2018-10-19 331-246 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 LEMONT IL

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.