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 503
QWEST CORPORATION 222
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
2005-09-12 503-934 0–9 XXXwhole prefix which blocks → QWEST CORPORATION 9638 SALEM OR
— 503-203 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-215 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-216 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-219 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-220 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-221 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-222 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-223 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-224 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-225 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-226 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-227 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-228 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-229 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-230 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-231 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-232 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-233 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-234 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-235 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-236 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-238 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-239 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-240 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-241 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-242 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-243 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-244 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-245 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-246 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-247 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-248 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-249 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-250 none assigned yet which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-251 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-252 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-253 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-254 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-255 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-256 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-257 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-258 7XXX which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-261 3XXX which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-262 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-273 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-274 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-275 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-276 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR
— 503-279 not yet reported which blocks → QWEST CORPORATION 9638 PORTLAND OR

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.