NumberResearchThousands-blocks in 423-391
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 423-391 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 423 blocks
Most active assignees, all time — NPA 423
New assignments by month
Sep 2026
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 423-391-0XXX | 0000–0999 | Reserved | UNITED TELEPHONE-SOUTHEAST-TN DBA CENTURYLINK - TN | 4510 | BLUFF CITY | TN |
| — | 423-391-1XXX | 1000–1999 | Reserved | UNITED TELEPHONE-SOUTHEAST-TN DBA CENTURYLINK - TN | 4510 | BLUFF CITY | TN |
| 2024-02-06 | 423-391-2XXX | 2000–2999 | Assigned | ONVOY SPECTRUM, LLC | 624H | BLUFF CITY | TN |
| 2006-10-31 | 423-391-3XXX | 3000–3999 | Assigned | UNITED TELEPHONE-SOUTHEAST-TN DBA CENTURYLINK - TN | 4510 | BLUFF CITY | TN |
| 2009-02-10 | 423-391-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - TN | 7278 | BLUFF CITY | TN |
| 2010-05-21 | 423-391-5XXX | 5000–5999 | Assigned | BANDWIDTH.COM CLEC, LLC - TN | 124F | BLUFF CITY | TN |
| 2010-09-08 | 423-391-6XXX | 6000–6999 | Assigned | BANDWIDTH.COM CLEC, LLC - TN | 124F | BLUFF CITY | TN |
| 2004-12-29 | 423-391-7XXX | 7000–7999 | Assigned | CHARTER IP ENABLED SERVICES, LLC | 792K | BLUFF CITY | TN |
| 2011-09-28 | 423-391-8XXX | 8000–8999 | Assigned | CHARTER IP ENABLED SERVICES, LLC | 792K | BLUFF CITY | TN |
| 2013-02-07 | 423-391-9XXX | 9000–9999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - TN | 4806 | BLUFF CITY | TN |
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.