NumberResearch Membership · Data 09/19/2026

Thousands-blocks in 231-853

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 231-853 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
FRONTIER NORTH, INC. - MI 5
LEVEL 3 COMMUNICATIONS, LLC - MI 2
MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 1
COMCAST IP PHONE, LLC 1
ACD TELECOM, INC. - MI 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
— 231-853-0XXX 0000–0999Reserved FRONTIER NORTH, INC. - MI 0695 RAVENNA MI
2012-11-06 231-853-1XXX 1000–1999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI 7157 RAVENNA MI
— 231-853-2XXX 2000–2999Reserved FRONTIER NORTH, INC. - MI 0695 RAVENNA MI
2004-10-14 231-853-3XXX 3000–3999Assigned LEVEL 3 COMMUNICATIONS, LLC - MI 6120 RAVENNA MI
2005-01-18 231-853-4XXX 4000–4999Assigned ACD TELECOM, INC. - MI 3535 RAVENNA MI
— 231-853-5XXX 5000–5999Reserved FRONTIER NORTH, INC. - MI 0695 RAVENNA MI
— 231-853-6XXX 6000–6999Reserved FRONTIER NORTH, INC. - MI 0695 RAVENNA MI
2005-12-30 231-853-7XXX 7000–7999Assigned LEVEL 3 COMMUNICATIONS, LLC - MI 6120 RAVENNA MI
— 231-853-8XXX 8000–8999Reserved FRONTIER NORTH, INC. - MI 0695 RAVENNA MI
2008-11-19 231-853-9XXX 9000–9999Assigned COMCAST IP PHONE, LLC 318J RAVENNA MI

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.