NumberResearchThousands-blocks in 435-554
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 435-554 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 435 blocks
Most active assignees, all time — NPA 435
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 |
|---|---|---|---|---|---|---|---|
| 2005-11-29 | 435-554-0XXX | 0000–0999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - UT | 3231 | LOGAN | UT |
| 2011-01-21 | 435-554-1XXX | 1000–1999 | Assigned | BANDWIDTH.COM CLEC, LLC - UT | 117F | LOGAN | UT |
| 2010-04-01 | 435-554-2XXX | 2000–2999 | Assigned | T-MOBILE USA, INC. | 6529 | LOGAN | UT |
| 2006-07-17 | 435-554-3XXX | 3000–3999 | Assigned | COMCAST IP PHONE, LLC | 318J | LOGAN | UT |
| 2010-04-01 | 435-554-4XXX | 4000–4999 | Assigned | T-MOBILE USA, INC. | 6529 | LOGAN | UT |
| 2010-04-01 | 435-554-5XXX | 5000–5999 | Assigned | T-MOBILE USA, INC. | 6529 | LOGAN | UT |
| 2010-04-01 | 435-554-6XXX | 6000–6999 | Assigned | T-MOBILE USA, INC. | 6529 | LOGAN | UT |
| 2006-10-10 | 435-554-7XXX | 7000–7999 | Assigned | ONVOY, LLC - UT | 871E | LOGAN | UT |
| 2008-10-30 | 435-554-8XXX | 8000–8999 | Assigned | BANDWIDTH.COM CLEC, LLC - UT | 117F | LOGAN | UT |
| 2010-04-01 | 435-554-9XXX | 9000–9999 | Assigned | T-MOBILE USA, INC. | 6529 | LOGAN | UT |
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.