NumberResearchThousands-blocks in 517-431
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
The ten 1,000-number thousand-blocks inside prefix 517-431 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
New assignments by month
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2005-08-03 | 517-431-0XXX | 0000–0999 | Assigned | TELNET WORLDWIDE, INC. | 817J | TIPTON | MI |
| 2011-08-29 | 517-431-1XXX | 1000–1999 | Assigned | DEERFIELD FARMERS' TELEPHONE COMPANY - MI | 558A | TIPTON | MI |
| — | 517-431-2XXX | 2000–2999 | Reserved | FRONTIER NORTH, INC. - MI | 0695 | TIPTON | MI |
| — | 517-431-3XXX | 3000–3999 | Reserved | FRONTIER NORTH, INC. - MI | 0695 | TIPTON | MI |
| 2007-02-08 | 517-431-4XXX | 4000–4999 | Assigned | ONVOY, LLCV - MI | 543C | TIPTON | MI |
| 2007-06-12 | 517-431-5XXX | 5000–5999 | Assigned | COMCAST IP PHONE, LLC | 318J | TIPTON | MI |
| 2010-10-08 | 517-431-6XXX | 6000–6999 | Assigned | TC3 TELECOM, INC. - MI | 3459 | TIPTON | MI |
| 2006-11-08 | 517-431-7XXX | 7000–7999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MI | 6120 | TIPTON | MI |
| — | 517-431-8XXX | 8000–8999 | Reserved | FRONTIER NORTH, INC. - MI | 0695 | TIPTON | MI |
| 2014-03-07 | 517-431-9XXX | 9000–9999 | Assigned | CENTURYLINK COMMUNICATIONS, LLC | 508J | TIPTON | MI |
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.