NumberResearchThousands-blocks in 251-501
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 251-501 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 251 blocks
Most active assignees, all time — NPA 251
New assignments by month
Sep 2026
Aug 2026
Jul 2026
Jun 2026
May 2026
Apr 2026
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Feb 2026
Jan 2026
Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2020-11-19 | 251-501-0XXX | 0000–0999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - GA | 6214 | MOBILE | AL |
| 2020-11-19 | 251-501-1XXX | 1000–1999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - GA | 6214 | MOBILE | AL |
| 2020-11-05 | 251-501-2XXX | 2000–2999 | Assigned | ONVOY, LLC - AL | 604E | MOBILE | AL |
| 2020-11-05 | 251-501-3XXX | 3000–3999 | Assigned | ONVOY, LLC - AL | 604E | MOBILE | AL |
| 2020-11-05 | 251-501-4XXX | 4000–4999 | Assigned | ONVOY, LLC - AL | 604E | MOBILE | AL |
| 2020-10-01 | 251-501-5XXX | 5000–5999 | Assigned | TWILIO INTERNATIONAL, INC. | 506J | MOBILE | AL |
| 2020-11-05 | 251-501-6XXX | 6000–6999 | Assigned | ONVOY, LLC - AL | 604E | MOBILE | AL |
| 2020-11-05 | 251-501-7XXX | 7000–7999 | Assigned | ONVOY, LLC - AL | 604E | MOBILE | AL |
| 2020-11-19 | 251-501-8XXX | 8000–8999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - GA | 6214 | MOBILE | AL |
| 2020-11-19 | 251-501-9XXX | 9000–9999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - GA | 6214 | MOBILE | AL |
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.