NumberResearchThousands-blocks in 231-391
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
The ten 1,000-number thousand-blocks inside prefix 231-391 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, last 30 days — NPA 231
New assignments by month
Sep 2026
Aug 2026
Jul 2026
Jun 2026
May 2026
Apr 2026
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Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2022-03-10 | 231-391-0XXX | 0000–0999 | Assigned | BANDWIDTH.COM CLEC, LLC - MI | 991E | WALLOON LK | MI |
| — | 231-391-1XXX | 1000–1999 | Available | WALLOON LK | MI | ||
| — | 231-391-2XXX | 2000–2999 | Available | WALLOON LK | MI | ||
| — | 231-391-3XXX | 3000–3999 | Available | WALLOON LK | MI | ||
| — | 231-391-4XXX | 4000–4999 | Available | WALLOON LK | MI | ||
| — | 231-391-5XXX | 5000–5999 | Available | WALLOON LK | MI | ||
| — | 231-391-6XXX | 6000–6999 | Available | WALLOON LK | MI | ||
| 2026-09-09 | 231-391-7XXX | 7000–7999 | Assigned | EXIANT COMMUNICATIONS LLC | 114J | WALLOON LK | MI |
| 2025-03-24 | 231-391-8XXX | 8000–8999 | Assigned | PEERLESS NETWORK OF MICHIGAN, LLC - MI | 933G | WALLOON LK | MI |
| 2023-09-29 | 231-391-9XXX | 9000–9999 | Assigned | PEERLESS NETWORK OF MICHIGAN, LLC - MI | 933G | WALLOON LK | 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.