NumberResearchThousands-blocks in 603-405
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 603-405 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 603 blocks
Most active assignees, all time — NPA 603
New assignments by month
Sep 2026
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2020-11-24 | 603-405-0XXX | 0000–0999 | Assigned | IDT AMERICA, CORP. - NH | 314C | SOMERSWTH | NH |
| 2024-06-05 | 603-405-1XXX | 1000–1999 | Assigned | TELNYX LLC | 073H | SOMERSWTH | NH |
| 2017-01-23 | 603-405-2XXX | 2000–2999 | Assigned | FREEDOM RING COMMUNICATIONS, LLC | 8468 | SOMERSWTH | NH |
| — | 603-405-3XXX | 3000–3999 | Available | SOMERSWTH | NH | ||
| — | 603-405-4XXX | 4000–4999 | Available | SOMERSWTH | NH | ||
| — | 603-405-5XXX | 5000–5999 | Available | SOMERSWTH | NH | ||
| 2016-04-21 | 603-405-6XXX | 6000–6999 | Assigned | TELEPORT COMMUNICATIONS AMERICA, LLC - NH | 8299 | SOMERSWTH | NH |
| — | 603-405-7XXX | 7000–7999 | Available | SOMERSWTH | NH | ||
| 2017-04-24 | 603-405-8XXX | 8000–8999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - DC | 4036 | SOMERSWTH | NH |
| — | 603-405-9XXX | 9000–9999 | Available | SOMERSWTH | NH |
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.