NumberResearchThousands-blocks in 231-321
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 231-321 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
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Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2023-07-07 | 231-321-0XXX | 0000–0999 | Assigned | ONVOY, LLCV - MI | 543C | ELMIRA | MI |
| 2024-09-17 | 231-321-1XXX | 1000–1999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MI | 6003 | ELMIRA | MI |
| — | 231-321-2XXX | 2000–2999 | Available | ELMIRA | MI | ||
| 2022-11-29 | 231-321-3XXX | 3000–3999 | Assigned | ONVOY, LLCV - MI | 543C | ELMIRA | MI |
| 2021-05-25 | 231-321-4XXX | 4000–4999 | Assigned | ONVOY SPECTRUM, LLC | 624H | ELMIRA | MI |
| 2021-06-11 | 231-321-5XXX | 5000–5999 | Assigned | ONVOY, LLCV - MI | 543C | ELMIRA | MI |
| — | 231-321-6XXX | 6000–6999 | Available | ELMIRA | MI | ||
| 2021-08-11 | 231-321-7XXX | 7000–7999 | Assigned | ONVOY, LLCV - MI | 543C | ELMIRA | MI |
| — | 231-321-8XXX | 8000–8999 | Available | ELMIRA | MI | ||
| — | 231-321-9XXX | 9000–9999 | Available | ELMIRA | 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.