NumberResearchThousands-blocks in 803-666
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 803-666 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 803 blocks
Most active assignees, all time — NPA 803
New assignments by month
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| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2004-10-20 | 803-666-0XXX | 0000–0999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - SC | 5258 | SHAWAFBHTS | SC |
| 2005-02-07 | 803-666-1XXX | 1000–1999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - SC | 5258 | SHAWAFBHTS | SC |
| — | 803-666-2XXX | 2000–2999 | Reserved | FRONTIER COMMUNICATIONS OF THE CAROLINAS INC. - SC | 4335 | SHAWAFBHTS | SC |
| — | 803-666-3XXX | 3000–3999 | Reserved | FRONTIER COMMUNICATIONS OF THE CAROLINAS INC. - SC | 4335 | SHAWAFBHTS | SC |
| — | 803-666-4XXX | 4000–4999 | Reserved | FRONTIER COMMUNICATIONS OF THE CAROLINAS INC. - SC | 4335 | SHAWAFBHTS | SC |
| 2006-09-19 | 803-666-5XXX | 5000–5999 | Assigned | TWC IP ENABLED SERVICES, LLC | 793K | SHAWAFBHTS | SC |
| 2004-09-14 | 803-666-6XXX | 6000–6999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - SC | 8534 | SHAWAFBHTS | SC |
| — | 803-666-7XXX | 7000–7999 | Reserved | FRONTIER COMMUNICATIONS OF THE CAROLINAS INC. - SC | 4335 | SHAWAFBHTS | SC |
| 2005-07-19 | 803-666-8XXX | 8000–8999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - SC | 5258 | SHAWAFBHTS | SC |
| — | 803-666-9XXX | 9000–9999 | Reserved | FRONTIER COMMUNICATIONS OF THE CAROLINAS INC. - SC | 4335 | SHAWAFBHTS | SC |
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.