NumberResearchThousands-blocks in 423-516
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 423-516 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
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2015-01-23 | 423-516-0XXX | 0000–0999 | Assigned | BANDWIDTH.COM CLEC, LLC - TN | 124F | SULIVNGDNS | TN |
| 2023-08-17 | 423-516-1XXX | 1000–1999 | Assigned | ONVOY, LLC - TN | 525E | SULIVNGDNS | TN |
| 2012-02-23 | 423-516-2XXX | 2000–2999 | Assigned | UNITED TELEPHONE-SOUTHEAST-TN DBA CENTURYLINK - TN | 4510 | SULIVNGDNS | TN |
| 2012-04-27 | 423-516-3XXX | 3000–3999 | Assigned | UNITED TELEPHONE-SOUTHEAST-TN DBA CENTURYLINK - TN | 4510 | SULIVNGDNS | TN |
| 2012-04-27 | 423-516-4XXX | 4000–4999 | Assigned | UNITED TELEPHONE-SOUTHEAST-TN DBA CENTURYLINK - TN | 4510 | SULIVNGDNS | TN |
| 2013-04-12 | 423-516-5XXX | 5000–5999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - TN | 7278 | SULIVNGDNS | TN |
| 2016-08-17 | 423-516-6XXX | 6000–6999 | Assigned | TELEPORT COMMUNICATIONS AMERICA, LLC - TN | 114F | SULIVNGDNS | TN |
| 2014-03-25 | 423-516-7XXX | 7000–7999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - TN | 4806 | SULIVNGDNS | TN |
| 2018-05-10 | 423-516-8XXX | 8000–8999 | Assigned | ONVOY, LLC - TN | 525E | SULIVNGDNS | TN |
| 2018-07-09 | 423-516-9XXX | 9000–9999 | Assigned | BANDWIDTH.COM CLEC, LLC - TN | 124F | SULIVNGDNS | TN |
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.