NumberResearch Membership · Data 09/20/2026

Thousands-blocks in 623-738

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 623-738 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 623 blocks

Most active assignees, all time — NPA 623
LEVEL 3 COMMUNICATIONS, LLC - AZ 4
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 3
BANDWIDTH.COM CLEC, LLC - AZ 3
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
Clear Download CSV ↓
Recent thousands-block assignments
AssignedThousands-blockLast 4 digitsStatusAssigneeOCNRate centerState
2009-05-20 623-738-0XXX 0000–0999Assigned LEVEL 3 COMMUNICATIONS, LLC - AZ 3285 PHOENIX AZ
2009-05-20 623-738-1XXX 1000–1999Assigned LEVEL 3 COMMUNICATIONS, LLC - AZ 3285 PHOENIX AZ
2009-05-20 623-738-2XXX 2000–2999Assigned LEVEL 3 COMMUNICATIONS, LLC - AZ 3285 PHOENIX AZ
2009-05-20 623-738-3XXX 3000–3999Assigned LEVEL 3 COMMUNICATIONS, LLC - AZ 3285 PHOENIX AZ
2010-03-29 623-738-4XXX 4000–4999Assigned BANDWIDTH.COM CLEC, LLC - AZ 587F PHOENIX AZ
2010-03-29 623-738-5XXX 5000–5999Assigned BANDWIDTH.COM CLEC, LLC - AZ 587F PHOENIX AZ
2010-03-29 623-738-6XXX 6000–6999Assigned BANDWIDTH.COM CLEC, LLC - AZ 587F PHOENIX AZ
2009-08-11 623-738-7XXX 7000–7999Assigned CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 PHOENIX AZ
2009-08-11 623-738-8XXX 8000–8999Assigned CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 PHOENIX AZ
2009-08-11 623-738-9XXX 9000–9999Assigned CELLCO PARTNERSHIP DBA VERIZON WIRELESS - AZ 6572 PHOENIX AZ

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.