NumberResearchThousands-blocks in 231-823
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
The ten 1,000-number thousand-blocks inside prefix 231-823 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
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
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 231-823-0XXX | 0000–0999 | Available | STANWOOD | MI | ||
| 2026-04-07 | 231-823-1XXX | 1000–1999 | Assigned | TERRA NOVA TELECOM INC. | 145J | STANWOOD | MI |
| — | 231-823-2XXX | 2000–2999 | Reserved | FRONTIER NORTH, INC. - MI | 0695 | STANWOOD | MI |
| — | 231-823-3XXX | 3000–3999 | Available | STANWOOD | MI | ||
| 2009-08-27 | 231-823-4XXX | 4000–4999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - IL | 6534 | STANWOOD | MI |
| 2005-01-18 | 231-823-5XXX | 5000–5999 | Assigned | ACD TELECOM, INC. - MI | 3535 | STANWOOD | MI |
| — | 231-823-6XXX | 6000–6999 | Available | STANWOOD | MI | ||
| 2013-02-20 | 231-823-7XXX | 7000–7999 | Assigned | ONVOY, LLCV - MI | 543C | STANWOOD | MI |
| — | 231-823-8XXX | 8000–8999 | Reserved | FRONTIER NORTH, INC. - MI | 0695 | STANWOOD | MI |
| — | 231-823-9XXX | 9000–9999 | Reserved | FRONTIER NORTH, INC. - MI | 0695 | STANWOOD | 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.