NumberResearchThousands-blocks in 559-521
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 559-521 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 559 blocks
Most active assignees, all time — NPA 559
New assignments by month
Sep 2026
Aug 2026
Jul 2026
Jun 2026
May 2026
Apr 2026
Mar 2026
Feb 2026
Jan 2026
Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 559-521-0XXX | 0000–0999 | Reserved | ONVOY, LLC - CA | 649C | DEL REY | CA |
| 2021-07-16 | 559-521-1XXX | 1000–1999 | Assigned | ONVOY, LLC - CA | 649C | DEL REY | CA |
| 2006-04-21 | 559-521-2XXX | 2000–2999 | Assigned | ONVOY, LLC - CA | 649C | DEL REY | CA |
| 2018-05-23 | 559-521-3XXX | 3000–3999 | Assigned | BANDWIDTH.COM CLEC, LLC - CA | 981E | DEL REY | CA |
| — | 559-521-4XXX | 4000–4999 | Available | DEL REY | CA | ||
| 2007-04-05 | 559-521-5XXX | 5000–5999 | Assigned | T-MOBILE USA, INC. | 6529 | DEL REY | CA |
| 2015-07-16 | 559-521-6XXX | 6000–6999 | Assigned | BANDWIDTH.COM CLEC, LLC - CA | 981E | DEL REY | CA |
| — | 559-521-7XXX | 7000–7999 | Available | DEL REY | CA | ||
| 2023-12-05 | 559-521-8XXX | 8000–8999 | Assigned | ONVOY SPECTRUM, LLC | 624H | DEL REY | CA |
| 2021-06-24 | 559-521-9XXX | 9000–9999 | Assigned | ONVOY, LLC - CA | 649C | DEL REY | CA |
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.