NumberResearch Membership · Data 09/19/2026

Thousands-blocks in 331-481

This prefix’s ten 1,000-number blocks and who holds each — 10 on record · from the daily NANPA thousands-block report, 09/19/2026

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

The ten 1,000-number thousand-blocks inside prefix 331-481 and who was initially assigned each. Under pooling these blocks often belong to different carriers — the single prefix-level “assignee” is usually just the pool / code holder, not who holds the numbers. ← all 331 blocks

Most active assignees, all time — NPA 331
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 3
LEVEL 3 COMMUNICATIONS, LLC - IL 2
BANDWIDTH.COM CLEC, LLC - IL 2
ONVOY, LLC 1
NEW CINGULAR WIRELESS PCS, LLC - IL 1
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
2008-10-30 331-481-0XXX 0000–0999Assigned CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 DOWNERSGRV IL
2009-01-23 331-481-1XXX 1000–1999Assigned NEW CINGULAR WIRELESS PCS, LLC - IL 6534 DOWNERSGRV IL
2009-08-20 331-481-2XXX 2000–2999Assigned CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 DOWNERSGRV IL
2009-04-20 331-481-3XXX 3000–3999Assigned CELLCO PARTNERSHIP DBA VERIZON WIRELESS - IL 6333 DOWNERSGRV IL
2009-01-26 331-481-4XXX 4000–4999Assigned ACCESS ONE, INC. - IL 5447 DOWNERSGRV IL
2010-02-12 331-481-5XXX 5000–5999Assigned ONVOY, LLC 224C DOWNERSGRV IL
2010-09-24 331-481-6XXX 6000–6999Assigned BANDWIDTH.COM CLEC, LLC - IL 984E DOWNERSGRV IL
2009-06-04 331-481-7XXX 7000–7999Assigned LEVEL 3 COMMUNICATIONS, LLC - IL 6115 DOWNERSGRV IL
2009-06-18 331-481-8XXX 8000–8999Assigned LEVEL 3 COMMUNICATIONS, LLC - IL 6115 DOWNERSGRV IL
2009-01-21 331-481-9XXX 9000–9999Assigned BANDWIDTH.COM CLEC, LLC - IL 984E DOWNERSGRV IL

Source: NANPA Thousands Block Assignment Report (All Regions, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.