NumberResearchThousands-blocks in 573-531
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 573-531 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 573 blocks
Most active assignees, all time — NPA 573
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 |
|---|---|---|---|---|---|---|---|
| 2020-07-15 | 573-531-0XXX | 0000–0999 | Assigned | TELNYX LLC | 073H | TIMBER | MO |
| — | 573-531-1XXX | 1000–1999 | Available | TIMBER | MO | ||
| 2019-10-24 | 573-531-2XXX | 2000–2999 | Assigned | ONVOY, LLC - MO | 093F | TIMBER | MO |
| 2019-10-24 | 573-531-3XXX | 3000–3999 | Assigned | ONVOY, LLC - MO | 093F | TIMBER | MO |
| 2021-02-04 | 573-531-4XXX | 4000–4999 | Assigned | ONVOY, LLC - MO | 093F | TIMBER | MO |
| 2018-11-08 | 573-531-5XXX | 5000–5999 | Assigned | ONVOY, LLC - MO | 093F | TIMBER | MO |
| — | 573-531-6XXX | 6000–6999 | Available | TIMBER | MO | ||
| 2013-09-18 | 573-531-7XXX | 7000–7999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MO | 4932 | TIMBER | MO |
| 2025-11-12 | 573-531-8XXX | 8000–8999 | Assigned | BANDWIDTH.COM CLEC, LLC - MO | 993E | TIMBER | MO |
| — | 573-531-9XXX | 9000–9999 | Available | TIMBER | MO |
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.