NumberResearchThousands-blocks in 423-817
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 423-817 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 |
|---|---|---|---|---|---|---|---|
| — | 423-817-0XXX | 0000–0999 | Reserved | SUNCOM DBA T-MOBILE USA | 8645 | KINGSPORT | TN |
| — | 423-817-1XXX | 1000–1999 | Reserved | METROPCS, INC. | 5562 | KINGSPORT | TN |
| — | 423-817-2XXX | 2000–2999 | Reserved | METROPCS, INC. | 5562 | KINGSPORT | TN |
| — | 423-817-3XXX | 3000–3999 | Reserved | METROPCS, INC. | 5562 | KINGSPORT | TN |
| 2025-10-17 | 423-817-4XXX | 4000–4999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - GA | 6214 | KINGSPORT | TN |
| 2008-03-06 | 423-817-5XXX | 5000–5999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | KINGSPORT | TN |
| 2022-09-26 | 423-817-6XXX | 6000–6999 | Assigned | COMMIO, LLC | 939H | KINGSPORT | TN |
| 2023-03-28 | 423-817-7XXX | 7000–7999 | Assigned | ONVOY SPECTRUM, LLC | 624H | KINGSPORT | TN |
| 2008-05-09 | 423-817-8XXX | 8000–8999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 6673 | KINGSPORT | TN |
| 2007-07-19 | 423-817-9XXX | 9000–9999 | Assigned | METROPCS, INC. | 5562 | KINGSPORT | 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.