NumberResearch Membership · Data 09/20/2026

Recent thousands-block assignments

0 blocks assigned in the last 30 days · from the daily NANPA thousands-block report, 09/20/2026

Full prefixes (NXX) Thousands-blocks (1,000-number pools)

Most carrier growth happens here, not at the prefix level: under number pooling, carriers receive individual 1,000-number blocks (e.g. 626-470-0XXX) within already-assigned prefixes. Assignments are initial assignments — the current serving carrier of individual numbers may differ due to portability.

Most active assignees, all time — NPA 517
AT&T ENTERPRISES, LLC 23
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 thousands-block assignments
AssignedThousands-blockLast 4 digitsStatusAssigneeOCNRate centerState
2023-08-29 517-310-7XXX 7000–7999Assigned AT&T ENTERPRISES, LLC 516C MULLIKEN MI
2016-08-22 517-664-0XXX 0000–0999Assigned AT&T ENTERPRISES, LLC 516C LANSING MI
2015-03-17 517-539-0XXX 0000–0999Assigned AT&T ENTERPRISES, LLC 516C JACKSON MI
2014-08-26 517-708-0XXX 0000–0999Assigned AT&T ENTERPRISES, LLC 516C LANSING MI
2013-10-10 517-878-3XXX 3000–3999Assigned AT&T ENTERPRISES, LLC 516C LESLIE MI
2012-12-07 517-763-2XXX 2000–2999Assigned AT&T ENTERPRISES, LLC 516C LANSING MI
2011-09-20 517-224-9XXX 9000–9999Assigned AT&T ENTERPRISES, LLC 516C POTTERVL MI
2011-09-20 517-305-6XXX 6000–6999Assigned AT&T ENTERPRISES, LLC 516C CLARKLAKE MI
2011-09-20 517-441-6XXX 6000–6999Assigned AT&T ENTERPRISES, LLC 516C EATON RPD MI
2011-09-20 517-615-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C VERMONTVL MI
2011-09-20 517-684-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C NAPOLEON MI
2011-09-20 517-715-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C FOWLERVL MI
2011-09-20 517-797-6XXX 6000–6999Assigned AT&T ENTERPRISES, LLC 516C HILLSDALE MI
2011-09-20 517-852-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C NASHVILLE MI
2011-09-20 517-883-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C MASON MI
2011-09-20 517-955-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C DANSVILLE MI
2011-09-20 517-983-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C CHARLOTTE MI
2011-09-20 517-995-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C JONESVILLE MI
2011-05-18 517-526-9XXX 9000–9999Assigned AT&T ENTERPRISES, LLC 516C PORTLAND MI
2010-12-08 517-235-7XXX 7000–7999Assigned AT&T ENTERPRISES, LLC 516C DIMONDALE MI
2009-12-22 517-465-7XXX 7000–7999Assigned AT&T ENTERPRISES, LLC 516C ALBION MI
2008-09-03 517-742-7XXX 7000–7999Assigned AT&T ENTERPRISES, LLC 516C HOLT MI
2006-02-02 517-618-7XXX 7000–7999Assigned AT&T ENTERPRISES, LLC 516C HOWELL MI

Source: NANPA Thousands Block Assignment Report (All Regions, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.