NumberResearchThousands-blocks in 231-267
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 231-267 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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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2005-01-18 | 231-267-0XXX | 0000–0999 | Assigned | ACD TELECOM, INC. - MI | 3535 | WILLIAMSBG | MI |
| 2005-08-03 | 231-267-1XXX | 1000–1999 | Assigned | TELNET WORLDWIDE, INC. | 817J | WILLIAMSBG | MI |
| 2021-04-14 | 231-267-2XXX | 2000–2999 | Assigned | ONVOY, LLCV - MI | 543C | WILLIAMSBG | MI |
| 2007-01-24 | 231-267-3XXX | 3000–3999 | Assigned | CHARTER IP ENABLED SERVICES, LLC | 792K | WILLIAMSBG | MI |
| 2009-09-04 | 231-267-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MI | 7157 | WILLIAMSBG | MI |
| — | 231-267-5XXX | 5000–5999 | Reserved | MICHIGAN BELL TEL CO | 9323 | WILLIAMSBG | MI |
| 2004-10-18 | 231-267-6XXX | 6000–6999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MI | 6120 | WILLIAMSBG | MI |
| 2004-01-12 | 231-267-7XXX | 7000–7999 | Assigned | PAETEC ITEL, LLC | 829J | WILLIAMSBG | MI |
| 2011-12-01 | 231-267-8XXX | 8000–8999 | Assigned | BANDWIDTH.COM CLEC, LLC - MI | 991E | WILLIAMSBG | MI |
| — | 231-267-9XXX | 9000–9999 | Reserved | MICHIGAN BELL TEL CO | 9323 | WILLIAMSBG | 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.