NumberResearchThousands-blocks in 231-674
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 231-674 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
May 2026
Apr 2026
Mar 2026
Feb 2026
Jan 2026
Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 231-674-0XXX | 0000–0999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - MI | 6120 | GRANT | MI |
| 2012-12-03 | 231-674-1XXX | 1000–1999 | Assigned | ONVOY, LLCV - MI | 543C | GRANT | MI |
| 2011-01-19 | 231-674-2XXX | 2000–2999 | Assigned | AT&T ENTERPRISES, LLC | 516C | GRANT | MI |
| 2012-05-04 | 231-674-3XXX | 3000–3999 | Assigned | ONVOY, LLCV - MI | 543C | GRANT | MI |
| 2004-06-22 | 231-674-4XXX | 4000–4999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MI | 6120 | GRANT | MI |
| 2014-08-05 | 231-674-5XXX | 5000–5999 | Assigned | BANDWIDTH.COM CLEC, LLC - MI | 991E | GRANT | MI |
| 2015-08-12 | 231-674-6XXX | 6000–6999 | Assigned | CENTURYLINK COMMUNICATIONS, LLC | 508J | GRANT | MI |
| 2014-10-01 | 231-674-7XXX | 7000–7999 | Assigned | ONVOY, LLCV - MI | 543C | GRANT | MI |
| 2016-02-19 | 231-674-8XXX | 8000–8999 | Assigned | ONVOY, LLCV - MI | 543C | GRANT | MI |
| — | 231-674-9XXX | 9000–9999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - MI | 6120 | GRANT | 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.