NumberResearchThousands-blocks in 508-503
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
The ten 1,000-number thousand-blocks inside prefix 508-503 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 508 blocks
Most active assignees, all time — NPA 508
New assignments by month
Sep 2026
Aug 2026
Jul 2026
Jun 2026
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Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 508-503-0XXX | 0000–0999 | Available | PLYMOUTH | MA | ||
| 2005-09-27 | 508-503-1XXX | 1000–1999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MA | 4018 | PLYMOUTH | MA |
| 2004-02-11 | 508-503-2XXX | 2000–2999 | Assigned | PAETEC ITEL, LLC | 829J | PLYMOUTH | MA |
| — | 508-503-3XXX | 3000–3999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - MA | 4018 | PLYMOUTH | MA |
| — | 508-503-4XXX | 4000–4999 | Available | PLYMOUTH | MA | ||
| 2024-01-04 | 508-503-5XXX | 5000–5999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC - DC | 4036 | PLYMOUTH | MA |
| 2016-02-25 | 508-503-6XXX | 6000–6999 | Assigned | ONVOY, LLC - MA | 892D | PLYMOUTH | MA |
| 2006-06-19 | 508-503-7XXX | 7000–7999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MA | 4018 | PLYMOUTH | MA |
| 2004-05-12 | 508-503-8XXX | 8000–8999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - MA | 4018 | PLYMOUTH | MA |
| 2024-10-17 | 508-503-9XXX | 9000–9999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MA | 6387 | PLYMOUTH | MA |
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.