NumberResearchThousands-blocks in 503-583
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 503-583 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
New assignments by month
Sep 2026
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2008-09-08 | 503-583-0XXX | 0000–0999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OR | 5820 | MCMINNVL | OR |
| 2008-10-08 | 503-583-1XXX | 1000–1999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC | 6010 | MCMINNVL | OR |
| 2009-01-09 | 503-583-2XXX | 2000–2999 | Assigned | BANDWIDTH.COM CLEC, LLC - OR | 076F | MCMINNVL | OR |
| 2009-01-29 | 503-583-3XXX | 3000–3999 | Assigned | T-MOBILE USA, INC. | 6529 | MCMINNVL | OR |
| 2010-01-20 | 503-583-4XXX | 4000–4999 | Assigned | BANDWIDTH.COM CLEC, LLC - OR | 076F | MCMINNVL | OR |
| 2009-07-20 | 503-583-5XXX | 5000–5999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - OR | 5820 | MCMINNVL | OR |
| 2010-01-25 | 503-583-6XXX | 6000–6999 | Assigned | T-MOBILE USA, INC. | 6529 | MCMINNVL | OR |
| 2010-06-11 | 503-583-7XXX | 7000–7999 | Assigned | T-MOBILE USA, INC. | 6529 | MCMINNVL | OR |
| 2010-09-03 | 503-583-8XXX | 8000–8999 | Assigned | BANDWIDTH.COM CLEC, LLC - OR | 076F | MCMINNVL | OR |
| 2009-06-01 | 503-583-9XXX | 9000–9999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC | 6010 | MCMINNVL | OR |
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.