NumberResearchThousands-blocks in 301-478
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 301-478 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 301 blocks
Most active assignees, all time — NPA 301
New assignments by month
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2004-02-26 | 301-478-0XXX | 0000–0999 | Assigned | CORE COMMUNICATIONS, INC.- MD | 2593 | FLINTSTONE | MD |
| 2006-02-10 | 301-478-1XXX | 1000–1999 | Assigned | IDT AMERICA, CORP. - MD | 228C | FLINTSTONE | MD |
| — | 301-478-2XXX | 2000–2999 | Reserved | VERIZON MARYLAND, INC. | 9212 | FLINTSTONE | MD |
| — | 301-478-3XXX | 3000–3999 | Reserved | VERIZON MARYLAND, INC. | 9212 | FLINTSTONE | MD |
| 2012-07-27 | 301-478-4XXX | 4000–4999 | Assigned | BANDWIDTH.COM CLEC, LLC - MD | 071F | FLINTSTONE | MD |
| — | 301-478-5XXX | 5000–5999 | Reserved | VERIZON MARYLAND, INC. | 9212 | FLINTSTONE | MD |
| 2015-02-03 | 301-478-6XXX | 6000–6999 | Assigned | BANDWIDTH.COM CLEC, LLC - MD | 071F | FLINTSTONE | MD |
| 2015-10-08 | 301-478-7XXX | 7000–7999 | Assigned | BANDWIDTH.COM CLEC, LLC - MD | 071F | FLINTSTONE | MD |
| 2016-08-30 | 301-478-8XXX | 8000–8999 | Assigned | ONVOY, LLC - MD | 876D | FLINTSTONE | MD |
| 2016-08-30 | 301-478-9XXX | 9000–9999 | Assigned | ONVOY, LLC - MD | 876D | FLINTSTONE | MD |
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.