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
— 573-406 none assigned yet which blocks → SOUTHWESTERN BELL 9533 HANNIBAL MO
— 573-422 4XXX5XXX8XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 VIENNA MO
— 573-431 not yet reported which blocks → SOUTHWESTERN BELL 9533 FLAT RIVER MO
— 573-448 0XXX4XXX6XXX7XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 GIDEON MO
— 573-455 0XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 WESTPHALIA MO
— 573-471 not yet reported which blocks → SOUTHWESTERN BELL 9533 SIKESTON MO
— 573-472 not yet reported which blocks → SOUTHWESTERN BELL 9533 SIKESTON MO
— 573-473 none assigned yet which blocks → SOUTHWESTERN BELL 9533 MEXICO MO
— 573-475 0XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 SIKESTON MO
— 573-481 2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 SIKESTON MO
— 573-483 0XXX4XXX5XXX6XXX8XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 BLOOMSDALE MO
— 573-484 2XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 BEAUFORT MO
— 573-517 4XXX6XXX8XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 PERRYVILLE MO
— 573-518 5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 FLAT RIVER MO
— 573-519 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-543 0XXX6XXX7XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 ST MARYS MO
— 573-545 0XXX2XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 BENTON MO
— 573-547 0XXX which blocks → SOUTHWESTERN BELL 9533 PERRYVILLE MO
— 573-562 0XXX3XXX5XXX6XXX8XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 LEADWOOD MO
— 573-564 0XXX4XXX5XXX7XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 MONTGORYCY MO
— 573-568 0XXX6XXX7XXX8XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 BLOOMFIELD MO
— 573-581 not yet reported which blocks → SOUTHWESTERN BELL 9533 MEXICO MO
— 573-582 9XXX which blocks → SOUTHWESTERN BELL 9533 MEXICO MO
— 573-592 9XXX which blocks → SOUTHWESTERN BELL 9533 FULTON MO
— 573-614 5XXX7XXX8XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 DEXTER MO
— 573-624 not yet reported which blocks → SOUTHWESTERN BELL 9533 DEXTER MO
— 573-628 0XXX2XXX6XXX7XXX8XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 WARDELL MO
— 573-642 not yet reported which blocks → SOUTHWESTERN BELL 9533 FULTON MO
— 573-643 3XXX4XXX5XXX7XXX8XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 MARSTON MO
— 573-649 0XXX4XXX6XXX7XXX8XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 E PRAIRIE MO
— 573-651 not yet reported which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-654 0XXX4XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 CARDWELL MO
— 573-667 0XXX2XXX3XXX4XXX6XXX7XXX8XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 MOREHOUSE MO
— 573-675 2XXX6XXX7XXX8XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 WYATT MO
— 573-678 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 RICHWOODS MO
— 573-683 8XXX9XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 CHARLESTON MO
— 573-684 3XXX4XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 WELLSVILLE MO
— 573-686 not yet reported which blocks → SOUTHWESTERN BELL 9533 POPLAR BLF MO
— 573-688 0XXX4XXX5XXX6XXX7XXX8XXX · 6 holders which blocks → SOUTHWESTERN BELL 9533 LILBOURN MO
— 573-701 none assigned yet which blocks → SOUTHWESTERN BELL 9533 FARMINGTON MO
— 573-717 4XXX5XXX9XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 KENNETT MO
— 573-720 0XXX3XXX4XXX5XXX6XXX7XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 BLYTHEVL MO
— 573-722 0XXX2XXX4XXX6XXX7XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 ADVANCE MO
— 573-727 1XXX3XXX4XXX6XXX7XXX8XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 POPLAR BLF MO
— 573-728 0XXX2XXX3XXX4XXX5XXX8XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 ARGYLE MO
— 573-730 0XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 CAPEGIRARD MO
— 573-733 0XXX2XXX3XXX5XXX6XXX7XXX8XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 BELL CITY MO
— 573-734 0XXX3XXX4XXX5XXX7XXX8XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 BISMARCK MO
— 573-737 0XXX3XXX5XXX7XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 HORNERSVL MO
— 573-738 0XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → SOUTHWESTERN BELL 9533 SENATH 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.