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 573
SOUTHWESTERN BELL 128
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
2010-11-11 573-755 0–9 XXXall 10 · 9 holders which blocks → SOUTHWESTERN BELL 9533 JACKSON MO
2006-03-28 573-878 0XXX1XXX2XXX3XXX4XXX5XXX8XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 BEAUFORT MO
2003-01-10 573-343 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 PUXICO MO
2001-07-11 573-583 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 ORAN MO
2001-06-15 573-629 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 HANNIBAL MO
2001-05-01 573-783 none assigned yet which blocks → SOUTHWESTERN BELL 9533 FREDERCKTN MO
— 573-204 3XXX4XXX5XXX6XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 JACKSON MO
— 573-218 0XXX2XXX3XXX4XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 FARMINGTON MO
— 573-221 not yet reported which blocks → SOUTHWESTERN BELL 9533 HANNIBAL MO
— 573-222 0XXX4XXX5XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 PUXICO MO
— 573-229 0XXX2XXX3XXX5XXX6XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 META MO
— 573-231 4XXX7XXX8XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 HANNIBAL MO
— 573-238 6XXX7XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 MARBLEHILL MO
— 573-242 0XXX2XXX4XXX5XXX6XXX8XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 CLARKSVL MO
— 573-243 not yet reported which blocks → SOUTHWESTERN BELL 9533 JACKSON MO
— 573-246 0XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 CAMPBELL MO
— 573-248 none assigned yet which blocks → SOUTHWESTERN BELL 9533 HANNIBAL MO
— 573-262 0XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 ORAN MO
— 573-264 0XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 SCOTT CITY MO
— 573-266 0XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 OAK RIDGE MO
— 573-267 0XXX2XXX4XXX5XXX6XXX8XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 CENTER MO
— 573-276 0XXX9XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 MALDEN MO
— 573-283 0XXX2XXX3XXX4XXX6XXX7XXX8XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 ESSEX MO
— 573-290 0XXX2XXX3XXX4XXX6XXX7XXX8XXX9XXX · 7 holders which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-302 5XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 LKOZKOSBCH MO
— 573-317 4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 CAMDENTON MO
— 573-324 0XXX7XXX8XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 BOWLNGGREN MO
— 573-327 0XXX1XXX2XXX3XXX4XXX6XXX8XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 FLAT RIVER MO
— 573-328 0XXX2XXX3XXX5XXX6XXX7XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 QULIN MO
— 573-331 9XXX which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-332 9XXX which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-333 3XXX7XXX8XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 CARUTHRSVL MO
— 573-334 not yet reported which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-335 not yet reported which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-339 3XXX which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-345 0XXX2XXX5XXX6XXX8XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 CLIMAX SPG MO
— 573-346 not yet reported which blocks → SOUTHWESTERN BELL 9533 CAMDENTON MO
— 573-347 0XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 CLIMAX SPG MO
— 573-348 not yet reported which blocks → SOUTHWESTERN BELL 9533 LKOZKOSBCH MO
— 573-358 6XXX9XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 BONNETERRE MO
— 573-359 8XXX which blocks → SOUTHWESTERN BELL 9533 HAYTI MO
— 573-363 0XXX2XXX3XXX4XXX6XXX8XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 MACKSCREEK MO
— 573-365 not yet reported which blocks → SOUTHWESTERN BELL 9533 LKOZKOSBCH MO
— 573-369 0XXX3XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 TUSCUMBIA MO
— 573-372 0XXX4XXX7XXX8XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 GRAVOIS ML MO
— 573-374 not yet reported which blocks → SOUTHWESTERN BELL 9533 GRAVOIS ML MO
— 573-378 not yet reported which blocks → SOUTHWESTERN BELL 9533 VERSAILLES MO
— 573-379 6XXX which blocks → SOUTHWESTERN BELL 9533 PORTAGEVL MO
— 573-392 not yet reported which blocks → SOUTHWESTERN BELL 9533 ELDON MO
— 573-396 0XXX3XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 RISCO MO

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.