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 623
T-MOBILE USA, INC. 39
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
Clear Download CSV ↓
Recent NPA-NXX prefix assignments
AssignedNPA-NXXThousands-blocks taken (last-4 opening)Code holderOCNRate centerState
2023-01-11 623-212 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2022-11-23 623-290 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2022-09-20 623-320 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2022-07-14 623-286 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2022-04-22 623-276 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2022-02-22 623-284 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2022-01-13 623-281 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2021-12-02 623-280 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2021-09-14 623-275 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2021-07-01 623-273 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2021-03-25 623-268 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2020-12-10 623-272 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2020-09-15 623-264 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2016-04-21 623-230 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2016-03-22 623-213 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2015-03-27 623-296 0–9 XXXwhole prefix which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2009-10-02 623-432 0–9 XXXall 10 · 6 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2008-07-23 623-552 0–9 XXXall 10 · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2007-09-07 623-239 0–9 XXXall 10 · 4 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2007-03-16 623-255 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2005-09-21 623-433 0–9 XXXall 10 · 3 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
2001-02-14 623-202 1XXX2XXX which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-210 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-217 0XXX2XXX · 2 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-221 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-261 0XXX which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-297 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-326 not yet reported which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-330 not yet reported which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-332 not yet reported which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-340 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-341 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-399 0–9 XXXall 10 · 5 holders which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-451 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-521 none assigned yet which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-533 3XXX4XXX5XXX6XXX which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-570 not yet reported which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-628 not yet reported which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ
— 623-703 5XXX8XXX which blocks → T-MOBILE USA, INC. 6529 PHOENIX AZ

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.