NumberResearchThousands-blocks in 406-551
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 406-551 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 406 blocks
Most active assignees, all time — NPA 406
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 |
|---|---|---|---|---|---|---|---|
| 2011-05-03 | 406-551-0XXX | 0000–0999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT | 6564 | BOZEMAN | MT |
| 2006-05-02 | 406-551-1XXX | 1000–1999 | Assigned | ONVOY, LLC - MT | 453F | BOZEMAN | MT |
| 2006-11-09 | 406-551-2XXX | 2000–2999 | Assigned | CHARTER IP ENABLED SERVICES, LLC | 792K | BOZEMAN | MT |
| 2011-05-03 | 406-551-3XXX | 3000–3999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT | 6564 | BOZEMAN | MT |
| — | 406-551-4XXX | 4000–4999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - MT | 9415 | BOZEMAN | MT |
| 2011-07-08 | 406-551-5XXX | 5000–5999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT | 6564 | BOZEMAN | MT |
| 2005-12-19 | 406-551-6XXX | 6000–6999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MT | 9415 | BOZEMAN | MT |
| 2014-09-30 | 406-551-7XXX | 7000–7999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MT | 9415 | BOZEMAN | MT |
| 2017-08-09 | 406-551-8XXX | 8000–8999 | Assigned | TRI TEL, INC. - MT | 935G | BOZEMAN | MT |
| 2011-10-27 | 406-551-9XXX | 9000–9999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MT | 9415 | BOZEMAN | MT |
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.