NumberResearch Membership · Data 09/20/2026

Thousands-blocks in 231-335

This prefix’s ten 1,000-number blocks and who holds each — 10 on record · from the daily NANPA thousands-block report, 09/20/2026

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

The ten 1,000-number thousand-blocks inside prefix 231-335 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 231 blocks

Most active assignees, all time — NPA 231
BANDWIDTH.COM CLEC, LLC - MI 4
OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 3
NEW CINGULAR WIRELESS PCS, LLC - IL 1
COMCAST IP PHONE, LLC 1
AT&T ENTERPRISES, LLC 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
— 231-335-0XXX 0000–0999Reserved NEW CINGULAR WIRELESS PCS, LLC - IL 6534 FREMONT MI
2014-02-26 231-335-1XXX 1000–1999Assigned BANDWIDTH.COM CLEC, LLC - MI 991E FREMONT MI
2007-05-08 231-335-2XXX 2000–2999Assigned COMCAST IP PHONE, LLC 318J FREMONT MI
2010-01-28 231-335-3XXX 3000–3999Assigned BANDWIDTH.COM CLEC, LLC - MI 991E FREMONT MI
2011-05-17 231-335-4XXX 4000–4999Assigned BANDWIDTH.COM CLEC, LLC - MI 991E FREMONT MI
2011-08-11 231-335-5XXX 5000–5999Assigned AT&T ENTERPRISES, LLC 516C FREMONT MI
2007-09-28 231-335-6XXX 6000–6999Assigned OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 FREMONT MI
2009-02-05 231-335-7XXX 7000–7999Assigned BANDWIDTH.COM CLEC, LLC - MI 991E FREMONT MI
2006-07-25 231-335-8XXX 8000–8999Assigned OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 FREMONT MI
2006-06-20 231-335-9XXX 9000–9999Assigned OMNIPOINT COMMUNICATIONS MIDWEST OPERATIONS, LLC 2964 FREMONT 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.