NumberResearch Membership · Data 09/19/2026

Recent prefix assignments

0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/19/2026

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
NEW CINGULAR WIRELESS PCS, LLC - IL 88
T-MOBILE USA, INC. 54
LEVEL 3 COMMUNICATIONS, LLC - TX 45
ONVOY, LLC - TX 43
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
— 817-509 none assigned yet which blocks → LEVEL 3 OF TELECOM OF TEXAS, LLC - TX 7516 FORT WORTH TX
— 817-510 3XXX4XXX6XXX7XXX8XXX · 2 holders which blocks → ONVOY, LLC - TX 903C EULESS TX
— 817-511 not yet reported which blocks → MULTIPLE OCN LISTING MULT XXXXXXXXXX TX
— 817-512 1XXX2XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → TEXAS WINDSTREAM, LLC 2153 CRESSON TX
— 817-514 not yet reported which blocks → SOUTHWESTERN BELL 9533 NRICHLDHLS TX
— 817-515 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-516 1XXX2XXX3XXX4XXX5XXX6XXX9XXX · 7 holders which blocks → SOUTHWESTERN BELL 9533 KENNEDALE TX
— 817-517 0XXX8XXX which blocks → SOUTHWESTERN BELL 9533 CLEBURNE TX
— 817-518 3XXX4XXX6XXX7XXX9XXX · 2 holders which blocks → ONVOY, LLC - TX 903C KELLER TX
— 817-519 not yet reported which blocks → U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS 671J NRICHLDHLS TX
— 817-520 0XXX1XXX2XXX3XXX4XXX · 2 holders which blocks → ONVOY, LLC - TX 903C NRICHLDHLS TX
— 817-521 none assigned yet which blocks → T-MOBILE USA, INC. 6529 ARLINGTON TX
— 817-522 1XXX2XXX3XXX4XXX6XXX8XXX · 2 holders which blocks → PAETEC ITEL, LLC 829J ARLINGTON TX
— 817-523 1XXX6XXX8XXX9XXX · 2 holders which blocks → FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS 2154 SPRINGTOWN TX
— 817-524 5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ARLINGTON TX
— 817-525 0XXX3XXX5XXX which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 ARLINGTON TX
— 817-526 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → PATHWAY COM-TEL, INC. - TX 8253 CLEBURNE TX
— 817-527 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 GRAPEVINE TX
— 817-528 not yet reported which blocks → CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TX 6506 ARLINGTON TX
— 817-529 not yet reported which blocks → ONVOY, LLC - TX 903C FORT WORTH TX
— 817-530 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-531 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-532 0XXX1XXX2XXX4XXX6XXX7XXX8XXX · 3 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - TX 6114 EULESS TX
— 817-533 5XXX8XXX · 2 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - TX 6114 ARLINGTON TX
— 817-534 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-535 9XXX which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-536 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-538 5XXX9XXX which blocks → T-MOBILE USA, INC. 6529 ARLINGTON TX
— 817-539 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 7 holders which blocks → SOUTHWESTERN BELL 9533 MANSFIELD TX
— 817-540 6XXX which blocks → SOUTHWESTERN BELL 9533 EULESS TX
— 817-541 0XXX1XXX2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → AT&T - LOCAL 7421 ROANOKE TX
— 817-542 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-543 2XXX which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-544 not yet reported which blocks → GRANDE COMMUNICATIONS NETWORKS, INC. - TX 7670 GRAPEVINE TX
— 817-545 not yet reported which blocks → SOUTHWESTERN BELL 9533 EULESS TX
— 817-546 3XXX5XXX6XXX7XXX8XXX which blocks → ONVOY, LLC - TX 903C FORT WORTH TX
— 817-547 0XXX which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-548 not yet reported which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-550 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 7 holders which blocks → LEVEL 3 COMMUNICATIONS, LLC - TX 6114 WEATHERFD TX
— 817-551 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-552 none assigned yet which blocks → ONVOY, LLC - TX 903C GRAPEVINE TX
— 817-553 0XXX4XXX7XXX9XXX · 2 holders which blocks → ONVOY, LLC - TX 903C EULESS TX
— 817-554 1XXX2XXX3XXX4XXX6XXX8XXX · 4 holders which blocks → PAETEC ITEL, LLC 829J EULESS TX
— 817-555 not yet reported which blocks → MULTIPLE OCN LISTING MULT DIR ASST TX
— 817-556 none assigned yet which blocks → SOUTHWESTERN BELL 9533 CLEBURNE TX
— 817-557 7XXX which blocks → SOUTHWESTERN BELL 9533 ARLINGTON TX
— 817-558 not yet reported which blocks → SOUTHWESTERN BELL 9533 CLEBURNE TX
— 817-560 not yet reported which blocks → SOUTHWESTERN BELL 9533 FORT WORTH TX
— 817-561 not yet reported which blocks → SOUTHWESTERN BELL 9533 KENNEDALE TX
— 817-562 0XXX6XXX7XXX9XXX · 3 holders which blocks → FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS 4344 KELLER TX

Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.