NumberResearch Membership · Data 09/20/2026

Thousands-blocks in 517-456

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 517-456 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 517 blocks

Most active assignees, all time — NPA 517
FRONTIER NORTH, INC. - MI 7
TELNET WORLDWIDE, INC. 1
COMCAST IP PHONE, LLC 1
ACD TELECOM, INC. - MI 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
2005-06-24 517-456-0XXX 0000–0999Assigned ACD TELECOM, INC. - MI 3535 CLINTON MI
— 517-456-1XXX 1000–1999Reserved FRONTIER NORTH, INC. - MI 0695 CLINTON MI
— 517-456-2XXX 2000–2999Reserved FRONTIER NORTH, INC. - MI 0695 CLINTON MI
2005-08-03 517-456-3XXX 3000–3999Assigned TELNET WORLDWIDE, INC. 817J CLINTON MI
— 517-456-4XXX 4000–4999Reserved FRONTIER NORTH, INC. - MI 0695 CLINTON MI
2007-06-13 517-456-5XXX 5000–5999Assigned COMCAST IP PHONE, LLC 318J CLINTON MI
— 517-456-6XXX 6000–6999Reserved FRONTIER NORTH, INC. - MI 0695 CLINTON MI
— 517-456-7XXX 7000–7999Reserved FRONTIER NORTH, INC. - MI 0695 CLINTON MI
— 517-456-8XXX 8000–8999Reserved FRONTIER NORTH, INC. - MI 0695 CLINTON MI
— 517-456-9XXX 9000–9999Reserved FRONTIER NORTH, INC. - MI 0695 CLINTON MI

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.