Thousands-blocks in 603-435

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

Full prefixes (NXX) Thousands-blocks (1,000-number pools)

The ten 1,000-number thousand-blocks inside prefix 603-435 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

CONSOLIDATED COMM OF NO. NEW ENGLAND-NH 5

PAETEC ITEL, LLC 1

LEVEL 3 COMMUNICATIONS, LLC - NH 1

IDT AMERICA, CORP. - NH 1

COMCAST IP PHONE, LLC 1

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

Recent thousands-block assignments
Assigned	Thousands-block	Last 4 digits	Status	Assignee	OCN	Rate center	State
2008-03-20	603-435-0XXX	0000–0999	Assigned	IDT AMERICA, CORP. - NH	314C	PITTSFIELD	NH
2001-10-04	603-435-1XXX	1000–1999	Assigned	PAETEC ITEL, LLC	829J	PITTSFIELD	NH
2002-09-07	603-435-2XXX	2000–2999	Assigned	BANDWIDTH.COM CLEC, LLC - NH	996E	PITTSFIELD	NH
2004-08-09	603-435-3XXX	3000–3999	Assigned	LEVEL 3 COMMUNICATIONS, LLC - NH	4017	PITTSFIELD	NH
2009-11-12	603-435-4XXX	4000–4999	Assigned	COMCAST IP PHONE, LLC	318J	PITTSFIELD	NH
—	603-435-5XXX	5000–5999	Reserved	CONSOLIDATED COMM OF NO. NEW ENGLAND-NH	5113	PITTSFIELD	NH
—	603-435-6XXX	6000–6999	Reserved	CONSOLIDATED COMM OF NO. NEW ENGLAND-NH	5113	PITTSFIELD	NH
—	603-435-7XXX	7000–7999	Reserved	CONSOLIDATED COMM OF NO. NEW ENGLAND-NH	5113	PITTSFIELD	NH
—	603-435-8XXX	8000–8999	Reserved	CONSOLIDATED COMM OF NO. NEW ENGLAND-NH	5113	PITTSFIELD	NH
—	603-435-9XXX	9000–9999	Reserved	CONSOLIDATED COMM OF NO. NEW ENGLAND-NH	5113	PITTSFIELD	NH

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.