Thousands-blocks in 603-255

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

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

The ten 1,000-number thousand-blocks inside prefix 603-255 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

ONVOY, LLC - NH 5

ONVOY SPECTRUM, LLC 2

TELEPORT COMMUNICATIONS AMERICA, LLC - NH 1

NUSO, LLC 1

CSC WIRELESS, 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
2021-12-08	603-255-0XXX	0000–0999	Assigned	ONVOY SPECTRUM, LLC	624H	MANCHESTER	NH
2021-12-08	603-255-1XXX	1000–1999	Assigned	ONVOY SPECTRUM, LLC	624H	MANCHESTER	NH
2020-02-20	603-255-2XXX	2000–2999	Assigned	CSC WIRELESS, LLC	425J	MANCHESTER	NH
2020-04-10	603-255-3XXX	3000–3999	Assigned	ONVOY, LLC - NH	637E	MANCHESTER	NH
2020-05-04	603-255-4XXX	4000–4999	Assigned	ONVOY, LLC - NH	637E	MANCHESTER	NH
2020-06-02	603-255-5XXX	5000–5999	Assigned	ONVOY, LLC - NH	637E	MANCHESTER	NH
2020-04-23	603-255-6XXX	6000–6999	Assigned	TELEPORT COMMUNICATIONS AMERICA, LLC - NH	8299	MANCHESTER	NH
2020-08-20	603-255-7XXX	7000–7999	Assigned	ONVOY, LLC - NH	637E	MANCHESTER	NH
2021-02-05	603-255-8XXX	8000–8999	Assigned	ONVOY, LLC - NH	637E	MANCHESTER	NH
2020-09-15	603-255-9XXX	9000–9999	Assigned	NUSO, LLC	478J	MANCHESTER	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.