NumberResearch Membership · Data 09/20/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/20/2026

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 312
T-MOBILE USA, INC. 64
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
2019-01-30 312-776 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-09-13 312-684 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-09-13 312-687 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-06-17 312-826 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-03-17 312-825 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-01-11 312-539 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2016-01-11 312-838 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-09-22 312-885 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-08-28 312-871 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-07-21 312-358 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-06-26 312-468 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-06-26 312-536 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2015-05-22 312-874 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-12-08 312-934 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-09-15 312-975 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-08-22 312-483 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-08-22 312-522 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-08-22 312-866 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2014-03-20 312-478 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2013-10-22 312-721 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2013-10-22 312-978 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2013-08-19 312-774 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2013-08-19 312-818 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2013-08-19 312-918 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2013-07-25 312-678 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2013-05-24 312-647 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2013-05-24 312-709 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2012-09-11 312-619 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2011-08-02 312-459 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2011-07-08 312-434 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2011-06-17 312-221 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2006-04-27 312-929 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2002-10-14 312-404 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2002-08-21 312-927 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2002-01-23 312-804 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
2001-07-06 312-735 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN04 IL
— 312-217 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-285 0XXX1XXX2XXX · 3 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-287 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN07 IL
— 312-296 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-340 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-371 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-375 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-388 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-399 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-437 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-446 none assigned yet which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-451 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-476 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL
— 312-493 not yet reported which blocks → T-MOBILE USA, INC. 6529 CHICGOZN01 IL

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.