NumberResearchThousands-blocks in 281-525
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 281-525 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 281 blocks
Most active assignees, all time — NPA 281
New assignments by month
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| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2015-12-09 | 281-525-0XXX | 0000–0999 | Assigned | IP HORIZON LLC | 515J | LEAGUECITY | TX |
| — | 281-525-1XXX | 1000–1999 | Reserved | FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS | 4344 | LEAGUECITY | TX |
| — | 281-525-2XXX | 2000–2999 | Reserved | FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS | 4344 | LEAGUECITY | TX |
| — | 281-525-3XXX | 3000–3999 | Reserved | FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS | 4344 | LEAGUECITY | TX |
| 2014-07-08 | 281-525-4XXX | 4000–4999 | Assigned | COMCAST IP PHONE, LLC | 318J | LEAGUECITY | TX |
| — | 281-525-5XXX | 5000–5999 | Reserved | FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS | 4344 | LEAGUECITY | TX |
| 2014-03-25 | 281-525-6XXX | 6000–6999 | Assigned | COMCAST IP PHONE, LLC | 318J | LEAGUECITY | TX |
| 2014-03-25 | 281-525-7XXX | 7000–7999 | Assigned | COMCAST IP PHONE, LLC | 318J | LEAGUECITY | TX |
| — | 281-525-8XXX | 8000–8999 | Reserved | TELEPORT COMMUNICATIONS AMERICA, LLC - TX | 7138 | LEAGUECITY | TX |
| 2015-02-26 | 281-525-9XXX | 9000–9999 | Assigned | IP HORIZON LLC | 515J | LEAGUECITY | TX |
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.