NumberResearch Membership · Data 09/21/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/21/2026

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 657
T-MOBILE USA, INC. 74
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
2016-08-26 657-345 0–9 XXXall 10 · 7 holders which blocks → T-MOBILE USA, INC. 6529 YORBALINDA CA
2016-08-09 657-342 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 HUNTITNBCH CA
2016-06-29 657-341 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 BREA CA
2016-06-17 657-335 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 SANTA ANA CA
2016-06-10 657-334 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 WESTMINSTR CA
2016-03-04 657-321 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 SANTA ANA CA
2015-11-23 657-296 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 GARDEN GRV CA
2015-10-19 657-445 0–9 XXXall 10 · 6 holders which blocks → T-MOBILE USA, INC. 6529 FULLERTON CA
2015-09-11 657-257 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 WESTMINSTR CA
2015-08-05 657-281 0–9 XXXall 10 · 7 holders which blocks → T-MOBILE USA, INC. 6529 ORANGE CA
2015-07-01 657-275 0–9 XXXall 10 · 7 holders which blocks → T-MOBILE USA, INC. 6529 PLACENTIA CA
2015-05-20 657-272 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 ANAHEIM CA
2015-05-11 657-266 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 SANTA ANA CA
2015-05-05 657-271 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 WESTMINSTR CA
2014-10-17 657-253 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 FULLERTON CA
2014-10-17 657-363 0–9 XXXall 10 · 6 holders which blocks → T-MOBILE USA, INC. 6529 YORBALINDA CA
2014-10-16 657-254 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 ANAHEIM CA
2014-09-23 657-252 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 BUENA PARK CA
2014-09-03 657-246 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 BREA CA
2014-04-28 657-238 0–9 XXXall 10 · 7 holders which blocks → T-MOBILE USA, INC. 6529 CYPRESS CA
2010-05-18 657-206 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 GARDEN GRV CA
— 657-347 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 ANAHEIM CA
— 657-357 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 SANTA ANA CA
— 657-456 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 ANAHEIM CA

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/21/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.