NumberResearchThousands-blocks in 443-733
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 443-733 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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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2003-01-21 | 443-733-0XXX | 0000–0999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 7229 | WATERLO238 | MD |
| 2003-02-07 | 443-733-1XXX | 1000–1999 | Assigned | PAETEC ITEL, LLC | 829J | WATERLO238 | MD |
| 2009-03-05 | 443-733-2XXX | 2000–2999 | Assigned | PAETEC ITEL, LLC | 829J | WATERLO238 | MD |
| 2008-09-11 | 443-733-3XXX | 3000–3999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - MD | 7228 | WATERLO238 | MD |
| 2016-03-29 | 443-733-4XXX | 4000–4999 | Assigned | ONVOY, LLC - MD | 876D | WATERLO238 | MD |
| 2013-09-12 | 443-733-5XXX | 5000–5999 | Assigned | PAETEC ITEL, LLC | 829J | WATERLO238 | MD |
| 2016-03-29 | 443-733-6XXX | 6000–6999 | Assigned | ONVOY, LLC - MD | 876D | WATERLO238 | MD |
| 2019-04-15 | 443-733-7XXX | 7000–7999 | Assigned | CORE COMMUNICATIONS, INC.- MD | 2593 | WATERLO238 | MD |
| 2016-05-03 | 443-733-8XXX | 8000–8999 | Assigned | IP HORIZON LLC | 515J | WATERLO238 | MD |
| — | 443-733-9XXX | 9000–9999 | Reserved | TELEPORT COMMUNICATIONS AMERICA, LLC - MD | 7325 | WATERLO238 | 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.