NumberResearchThousands-blocks in 510-250
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 510-250 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 510 blocks
Most active assignees, all time — NPA 510
New assignments by month
Sep 2026
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 510-250-0XXX | 0000–0999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | OKLD MN-PD | CA |
| — | 510-250-1XXX | 1000–1999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | OKLD MN-PD | CA |
| 2008-05-06 | 510-250-2XXX | 2000–2999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | OKLD MN-PD | CA |
| 2008-05-06 | 510-250-3XXX | 3000–3999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | OKLD MN-PD | CA |
| 2006-07-14 | 510-250-4XXX | 4000–4999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | OKLD MN-PD | CA |
| — | 510-250-5XXX | 5000–5999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | OKLD MN-PD | CA |
| 2007-02-27 | 510-250-6XXX | 6000–6999 | Assigned | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD MN-PD | CA |
| 2007-11-21 | 510-250-7XXX | 7000–7999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | OKLD MN-PD | CA |
| 2007-02-27 | 510-250-8XXX | 8000–8999 | Assigned | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | OKLD MN-PD | CA |
| 2011-09-20 | 510-250-9XXX | 9000–9999 | Assigned | AT&T ENTERPRISES, LLC | 516C | OKLD MN-PD | CA |
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.