NumberResearchThousands-blocks in 231-475
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 231-475 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
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2021-08-19 | 231-475-0XXX | 0000–0999 | Assigned | BANDWIDTH.COM CLEC, LLC - MI | 991E | MANTON | MI |
| 2024-04-25 | 231-475-1XXX | 1000–1999 | Assigned | ONVOY SPECTRUM, LLC | 624H | MANTON | MI |
| 2024-01-10 | 231-475-2XXX | 2000–2999 | Assigned | TERRA NOVA TELECOM INC. | 145J | MANTON | MI |
| — | 231-475-3XXX | 3000–3999 | Available | MANTON | MI | ||
| — | 231-475-4XXX | 4000–4999 | Available | MANTON | MI | ||
| — | 231-475-5XXX | 5000–5999 | Available | MANTON | MI | ||
| — | 231-475-6XXX | 6000–6999 | Available | MANTON | MI | ||
| 2023-08-25 | 231-475-7XXX | 7000–7999 | Assigned | AT&T ENTERPRISES, LLC | 516C | MANTON | MI |
| 2023-09-29 | 231-475-8XXX | 8000–8999 | Assigned | PEERLESS NETWORK OF MICHIGAN, LLC - MI | 933G | MANTON | MI |
| 2021-12-15 | 231-475-9XXX | 9000–9999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - IL | 6534 | MANTON | 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.