NumberResearchThousands-blocks in 443-731
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 443-731 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
Aug 2026
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Jun 2026
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Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2024-02-06 | 443-731-0XXX | 0000–0999 | Assigned | ONVOY, LLC - MD | 876D | PT DEPOSIT | MD |
| 2008-06-02 | 443-731-1XXX | 1000–1999 | Assigned | ARMSTRONG TELECOMMUNICATIONS, INC. - MD | 420C | PT DEPOSIT | MD |
| 2006-02-08 | 443-731-2XXX | 2000–2999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MD | 6119 | PT DEPOSIT | MD |
| 2008-11-07 | 443-731-3XXX | 3000–3999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MD | 6119 | PT DEPOSIT | MD |
| 2017-07-10 | 443-731-4XXX | 4000–4999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD | 7228 | PT DEPOSIT | MD |
| 2018-05-21 | 443-731-5XXX | 5000–5999 | Assigned | ONVOY, LLC - MD | 876D | PT DEPOSIT | MD |
| 2008-11-12 | 443-731-6XXX | 6000–6999 | Assigned | BANDWIDTH.COM CLEC, LLC - MD | 071F | PT DEPOSIT | MD |
| 2016-04-20 | 443-731-7XXX | 7000–7999 | Assigned | HD CARRIER LLC | 321J | PT DEPOSIT | MD |
| 2024-01-08 | 443-731-8XXX | 8000–8999 | Assigned | TERRA NOVA TELECOM INC. | 145J | PT DEPOSIT | MD |
| — | 443-731-9XXX | 9000–9999 | Reserved | TELEPORT COMMUNICATIONS AMERICA, LLC - MD | 7325 | PT DEPOSIT | 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.