NumberResearch Membership · Data 09/19/2026

Thousands-blocks in 203-403

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 203-403 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 203 blocks

Most active assignees, all time — NPA 203
LEVEL 3 COMMUNICATIONS, LLC - CT 4
BANDWIDTH.COM CLEC, LLC - CT 2
TELEPORT COMMUNICATIONS AMERICA, LLC - CT 1
SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 1
PAETEC ITEL, 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
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Recent thousands-block assignments
AssignedThousands-blockLast 4 digitsStatusAssigneeOCNRate centerState
2014-03-20 203-403-0XXX 0000–0999Assigned BANDWIDTH.COM CLEC, LLC - CT 199F RIDGEFIELD CT
— 203-403-1XXX 1000–1999Reserved TELEPORT COMMUNICATIONS AMERICA, LLC - CT 7143 RIDGEFIELD CT
2008-05-01 203-403-2XXX 2000–2999Assigned LEVEL 3 COMMUNICATIONS, LLC - CT 4800 RIDGEFIELD CT
2008-11-14 203-403-3XXX 3000–3999Assigned COMCAST IP PHONE, LLC 318J RIDGEFIELD CT
2004-09-15 203-403-4XXX 4000–4999Assigned PAETEC ITEL, LLC 829J RIDGEFIELD CT
2007-08-10 203-403-5XXX 5000–5999Assigned SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT 9147 RIDGEFIELD CT
2011-02-04 203-403-6XXX 6000–6999Assigned LEVEL 3 COMMUNICATIONS, LLC - CT 4800 RIDGEFIELD CT
2012-05-11 203-403-7XXX 7000–7999Assigned BANDWIDTH.COM CLEC, LLC - CT 199F RIDGEFIELD CT
2013-10-09 203-403-8XXX 8000–8999Assigned LEVEL 3 COMMUNICATIONS, LLC - CT 4800 RIDGEFIELD CT
2001-04-17 203-403-9XXX 9000–9999Assigned LEVEL 3 COMMUNICATIONS, LLC - CT 4800 RIDGEFIELD CT

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.