NumberResearch Membership · Data 09/19/2026

Thousands-blocks in 503-427

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 503-427 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 503 blocks

Most active assignees, all time — NPA 503
ELECTRIC LIGHTWAVE LLC DBA ALLSTREAM 3
MCIMETRO ACCESS TRANSMISSION SERVICES LLC 2
LEVEL 3 COMMUNICATIONS, LLC - OR 2
COMCAST IP PHONE, LLC 2
BANDWIDTH.COM CLEC, LLC - OR 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
2006-01-12 503-427-0XXX 0000–0999Assigned COMCAST IP PHONE, LLC 318J STFRD-SNDY OR
— 503-427-1XXX 1000–1999Reserved LEVEL 3 COMMUNICATIONS, LLC - OR 3234 STFRD-SNDY OR
2009-03-31 503-427-2XXX 2000–2999Assigned COMCAST IP PHONE, LLC 318J STFRD-SNDY OR
2005-03-10 503-427-3XXX 3000–3999Assigned ELECTRIC LIGHTWAVE LLC DBA ALLSTREAM 7172 STFRD-SNDY OR
2005-03-10 503-427-4XXX 4000–4999Assigned ELECTRIC LIGHTWAVE LLC DBA ALLSTREAM 7172 STFRD-SNDY OR
2005-03-10 503-427-5XXX 5000–5999Assigned ELECTRIC LIGHTWAVE LLC DBA ALLSTREAM 7172 STFRD-SNDY OR
2007-05-02 503-427-6XXX 6000–6999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 STFRD-SNDY OR
2004-09-10 503-427-7XXX 7000–7999Assigned MCIMETRO ACCESS TRANSMISSION SERVICES LLC 7229 STFRD-SNDY OR
2008-10-30 503-427-8XXX 8000–8999Assigned BANDWIDTH.COM CLEC, LLC - OR 076F STFRD-SNDY OR
2011-02-24 503-427-9XXX 9000–9999Assigned LEVEL 3 COMMUNICATIONS, LLC - OR 3234 STFRD-SNDY OR

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.