NumberResearchThousands-blocks in 603-575
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 603-575 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
Aug 2026
Jul 2026
Jun 2026
May 2026
Apr 2026
Mar 2026
Feb 2026
Jan 2026
Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2019-04-19 | 603-575-0XXX | 0000–0999 | Assigned | TELEPORT COMMUNICATIONS AMERICA, LLC - NH | 8299 | LITTLETON | NH |
| 2019-06-26 | 603-575-1XXX | 1000–1999 | Assigned | BELL ATLANTIC MOBILE, INC | 6386 | LITTLETON | NH |
| — | 603-575-2XXX | 2000–2999 | Available | LITTLETON | NH | ||
| 2025-12-11 | 603-575-3XXX | 3000–3999 | Assigned | OMNIPOINT MIAMI E LICENSE, LLC | 6889 | LITTLETON | NH |
| — | 603-575-4XXX | 4000–4999 | Available | LITTLETON | NH | ||
| 2012-07-30 | 603-575-5XXX | 5000–5999 | Assigned | TWC IP ENABLED SERVICES, LLC | 793K | LITTLETON | NH |
| 2013-10-09 | 603-575-6XXX | 6000–6999 | Assigned | PAETEC ITEL, LLC | 829J | LITTLETON | NH |
| 2025-02-17 | 603-575-7XXX | 7000–7999 | Assigned | OMNIPOINT MIAMI E LICENSE, LLC | 6889 | LITTLETON | NH |
| — | 603-575-8XXX | 8000–8999 | Available | LITTLETON | NH | ||
| — | 603-575-9XXX | 9000–9999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NH | 7778 | LITTLETON | 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.