NumberResearchThousands-blocks in 423-437
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 423-437 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
Aug 2026
Jul 2026
Jun 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 |
|---|---|---|---|---|---|---|---|
| — | 423-437-0XXX | 0000–0999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - TN | 4806 | LAFOLLETTE | TN |
| 2007-07-11 | 423-437-1XXX | 1000–1999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | LAFOLLETTE | TN |
| 2008-09-05 | 423-437-2XXX | 2000–2999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | LAFOLLETTE | TN |
| 2008-05-22 | 423-437-3XXX | 3000–3999 | Assigned | ONVOY, LLC - TN | 525E | LAFOLLETTE | TN |
| — | 423-437-4XXX | 4000–4999 | Available | LAFOLLETTE | TN | ||
| 2025-07-29 | 423-437-5XXX | 5000–5999 | Assigned | TWC IP ENABLED SERVICES, LLC | 793K | LAFOLLETTE | TN |
| — | 423-437-6XXX | 6000–6999 | Available | LAFOLLETTE | TN | ||
| 2009-01-06 | 423-437-7XXX | 7000–7999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | LAFOLLETTE | TN |
| 2011-08-08 | 423-437-8XXX | 8000–8999 | Assigned | COMCAST IP PHONE, LLC | 318J | LAFOLLETTE | TN |
| 2021-11-02 | 423-437-9XXX | 9000–9999 | Assigned | ONVOY, LLC - TN | 525E | LAFOLLETTE | 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.