NumberResearchThousands-blocks in 443-507
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 443-507 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 443 blocks
Most active assignees, all time — NPA 443
New assignments by month
Sep 2026
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Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2003-09-11 | 443-507-0XXX | 0000–0999 | Assigned | VERIZON MARYLAND, INC. | 9212 | HAMPSTEAD | MD |
| 2003-06-26 | 443-507-1XXX | 1000–1999 | Assigned | PAETEC ITEL, LLC | 829J | HAMPSTEAD | MD |
| — | 443-507-2XXX | 2000–2999 | Available | HAMPSTEAD | MD | ||
| 2004-03-01 | 443-507-3XXX | 3000–3999 | Assigned | CORE COMMUNICATIONS, INC.- MD | 2593 | HAMPSTEAD | MD |
| 2016-01-04 | 443-507-4XXX | 4000–4999 | Assigned | QUANTUM TELECOMMUNICATIONS, INC. - MD | 2596 | HAMPSTEAD | MD |
| 2005-04-22 | 443-507-5XXX | 5000–5999 | Assigned | VERIZON MARYLAND, INC. | 9212 | HAMPSTEAD | MD |
| 2009-05-15 | 443-507-6XXX | 6000–6999 | Assigned | COMCAST IP PHONE, LLC | 318J | HAMPSTEAD | MD |
| 2024-01-17 | 443-507-7XXX | 7000–7999 | Assigned | TERRA NOVA TELECOM INC. | 145J | HAMPSTEAD | MD |
| 2011-06-07 | 443-507-8XXX | 8000–8999 | Assigned | BANDWIDTH.COM CLEC, LLC - MD | 071F | HAMPSTEAD | MD |
| — | 443-507-9XXX | 9000–9999 | Reserved | TELEPORT COMMUNICATIONS AMERICA, LLC - MD | 7325 | HAMPSTEAD | MD |
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.