NumberResearchThousands-blocks in 531-600
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 531-600 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 531 blocks
Most active assignees, all time — NPA 531
New assignments by month
Sep 2026
Aug 2026
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Jun 2026
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Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2015-04-10 | 531-600-0XXX | 0000–0999 | Assigned | BANDWIDTH.COM CLEC, LLC - NE | 995E | OMAHA | NE |
| 2015-04-10 | 531-600-1XXX | 1000–1999 | Assigned | BANDWIDTH.COM CLEC, LLC - NE | 995E | OMAHA | NE |
| 2015-04-10 | 531-600-2XXX | 2000–2999 | Assigned | BANDWIDTH.COM CLEC, LLC - NE | 995E | OMAHA | NE |
| 2015-04-10 | 531-600-3XXX | 3000–3999 | Assigned | BANDWIDTH.COM CLEC, LLC - NE | 995E | OMAHA | NE |
| 2015-06-25 | 531-600-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 7229 | OMAHA | NE |
| 2015-07-23 | 531-600-5XXX | 5000–5999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - NE | 3233 | OMAHA | NE |
| 2015-08-10 | 531-600-6XXX | 6000–6999 | Assigned | COMCAST IP PHONE, LLC | 318J | OMAHA | NE |
| 2015-03-17 | 531-600-7XXX | 7000–7999 | Assigned | ALLO COMMUNICATIONS LLC | 907K | OMAHA | NE |
| 2015-04-10 | 531-600-8XXX | 8000–8999 | Assigned | BANDWIDTH.COM CLEC, LLC - NE | 995E | OMAHA | NE |
| 2015-04-10 | 531-600-9XXX | 9000–9999 | Assigned | BANDWIDTH.COM CLEC, LLC - NE | 995E | OMAHA | NE |
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.