NumberResearchThousands-blocks in 310-584
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 310-584 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 310 blocks
Most active assignees, all time — NPA 310
New assignments by month
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 310-584-0XXX | 0000–0999 | Reserved | FRONTIER CALIFORNIA INC. | 2319 | SNMN SNMN | CA |
| 2005-08-23 | 310-584-1XXX | 1000–1999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SNMN SNMN | CA |
| — | 310-584-2XXX | 2000–2999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 7229 | SNMN SNMN | CA |
| — | 310-584-3XXX | 3000–3999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 7229 | SNMN SNMN | CA |
| 2005-08-23 | 310-584-4XXX | 4000–4999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SNMN SNMN | CA |
| — | 310-584-5XXX | 5000–5999 | Reserved | FRONTIER CALIFORNIA INC. | 2319 | SNMN SNMN | CA |
| 2022-02-25 | 310-584-6XXX | 6000–6999 | Assigned | ONVOY SPECTRUM, LLC | 624H | SNMN SNMN | CA |
| 2006-05-05 | 310-584-7XXX | 7000–7999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SNMN SNMN | CA |
| 2000-05-10 | 310-584-8XXX | 8000–8999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | SNMN SNMN | CA |
| 2000-03-24 | 310-584-9XXX | 9000–9999 | Assigned | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | SNMN SNMN | 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.