NumberResearchThousands-blocks in 231-570
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 231-570 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
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Dec 2025
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 231-570-0XXX | 0000–0999 | Reserved | NEW CINGULAR WIRELESS PCS, LLC - IL | 6534 | FIFE LAKE | MI |
| 2005-01-12 | 231-570-1XXX | 1000–1999 | Assigned | ACD TELECOM, INC. - MI | 3535 | FIFE LAKE | MI |
| 2009-04-10 | 231-570-2XXX | 2000–2999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - IL | 6534 | FIFE LAKE | MI |
| 2012-03-06 | 231-570-3XXX | 3000–3999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - IL | 6534 | FIFE LAKE | MI |
| 2012-10-22 | 231-570-4XXX | 4000–4999 | Assigned | BANDWIDTH.COM CLEC, LLC - MI | 991E | FIFE LAKE | MI |
| 2013-03-20 | 231-570-5XXX | 5000–5999 | Assigned | ONVOY, LLCV - MI | 543C | FIFE LAKE | MI |
| 2016-02-19 | 231-570-6XXX | 6000–6999 | Assigned | ONVOY, LLCV - MI | 543C | FIFE LAKE | MI |
| 2011-08-11 | 231-570-7XXX | 7000–7999 | Assigned | AT&T ENTERPRISES, LLC | 516C | FIFE LAKE | MI |
| 2004-06-15 | 231-570-8XXX | 8000–8999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MI | 6120 | FIFE LAKE | MI |
| 2016-02-19 | 231-570-9XXX | 9000–9999 | Assigned | ONVOY, LLCV - MI | 543C | FIFE LAKE | 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.