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 817
SOUTHWESTERN BELL 302
SOUTHWESTERN BELL TELEPHONE COMPANY - TX 3
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
— 817-378 4XXX6XXX7XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-385 1XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-387 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-390 0XXX which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-399 not yet reported which blocks → SOUTHWESTERN BELL 9533 EULESS TX
— 817-404 2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-408 0XXX5XXX6XXX which blocks → SOUTHWESTERN BELL 9533 GRANBURY TX
— 817-412 0XXX1XXX3XXX4XXX7XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-413 1XXX7XXX8XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-415 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-417 9XXX which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-419 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-420 0XXX2XXX3XXX4XXX6XXX7XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-423 3XXX6XXX7XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-426 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-427 5XXX which blocks → SOUTHWESTERN BELL 9533 NRICHLDHLS TX
— 817-428 not yet reported which blocks → SOUTHWESTERN BELL 9533 NRICHLDHLS TX
— 817-429 not yet reported which blocks → SOUTHWESTERN BELL 9533 GLENDALE TX
— 817-430 not yet reported which blocks → SOUTHWESTERN BELL 9533 ROANOKE TX
— 817-433 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-436 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-439 6XXX7XXX9XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-441 0XXX3XXX which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-443 1XXX2XXX4XXX5XXX7XXX8XXX which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-446 9XXX which blocks → SOUTHWESTERN BELL 9533 GLENDALE TX
— 817-447 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-448 1XXX2XXX3XXX4XXX5XXX7XXX which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-449 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-451 not yet reported which blocks → SOUTHWESTERN BELL 9533 GLENDALE TX
— 817-453 not yet reported which blocks → SOUTHWESTERN BELL 9533 MANSFIELD TX
— 817-457 not yet reported which blocks → SOUTHWESTERN BELL 9533 GLENDALE TX
— 817-459 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-460 9XXX which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-461 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-462 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-465 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-466 6XXX which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-467 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-468 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-469 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-472 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-473 not yet reported which blocks → SOUTHWESTERN BELL 9533 MANSFIELD TX
— 817-474 0XXX which blocks → SOUTHWESTERN BELL 9533 ROANOKE TX
— 817-477 6XXX7XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 MANSFIELD TX
— 817-478 not yet reported which blocks → SOUTHWESTERN BELL 9533 KENNEDALE TX
— 817-483 not yet reported which blocks → SOUTHWESTERN BELL 9533 KENNEDALE TX
— 817-485 not yet reported which blocks → SOUTHWESTERN BELL 9533 NRICHLDHLS TX
— 817-489 0XXX3XXX4XXX5XXX8XXX9XXX · 4 holders which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-490 not yet reported which blocks → SOUTHWESTERN BELL 9533 ROANOKE TX
— 817-491 not yet reported which blocks → SOUTHWESTERN BELL 9533 ROANOKE TX

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.