NumberResearchThousands-blocks in 603-389
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 603-389 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 |
|---|---|---|---|---|---|---|---|
| 2001-03-13 | 603-389-0XXX | 0000–0999 | Assigned | PAETEC ITEL, LLC | 829J | DURHAM | NH |
| 2005-02-08 | 603-389-1XXX | 1000–1999 | Assigned | PAETEC ITEL, LLC | 829J | DURHAM | NH |
| 2007-06-27 | 603-389-2XXX | 2000–2999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - NH | 7778 | DURHAM | NH |
| 2006-08-10 | 603-389-3XXX | 3000–3999 | Assigned | OTEL TELEKOM, INC. - NH | 9827 | DURHAM | NH |
| — | 603-389-4XXX | 4000–4999 | Available | DURHAM | NH | ||
| — | 603-389-5XXX | 5000–5999 | Available | DURHAM | NH | ||
| 2010-09-03 | 603-389-6XXX | 6000–6999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - NH | 4017 | DURHAM | NH |
| 2015-10-29 | 603-389-7XXX | 7000–7999 | Assigned | BELL ATLANTIC MOBILE, INC | 6386 | DURHAM | NH |
| 2008-03-20 | 603-389-8XXX | 8000–8999 | Assigned | IDT AMERICA, CORP. - NH | 314C | DURHAM | NH |
| 2000-08-02 | 603-389-9XXX | 9000–9999 | Assigned | PAETEC ITEL, LLC | 829J | DURHAM | 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.