NumberResearchThousands-blocks in 253-478
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 253-478 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 253 blocks
Most active assignees, all time — NPA 253
New assignments by month
Sep 2026
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2015-05-28 | 253-478-0XXX | 0000–0999 | Assigned | METROPCS, INC. | 5562 | KENT | WA |
| — | 253-478-1XXX | 1000–1999 | Reserved | LEVEL 3 TELECOM OF WASHINGTON, LLC - WA | 7455 | KENT | WA |
| 2020-11-11 | 253-478-2XXX | 2000–2999 | Assigned | TELNYX LLC | 073H | KENT | WA |
| 2015-10-29 | 253-478-3XXX | 3000–3999 | Assigned | COMCAST IP PHONE, LLC | 318J | KENT | WA |
| — | 253-478-4XXX | 4000–4999 | Reserved | LEVEL 3 TELECOM OF WASHINGTON, LLC - WA | 7455 | KENT | WA |
| 2004-01-13 | 253-478-5XXX | 5000–5999 | Assigned | ELECTRIC LIGHTWAVE LLC DBA ALLSTREAM | 7173 | KENT | WA |
| 2016-06-15 | 253-478-6XXX | 6000–6999 | Assigned | METROPCS, INC. | 5562 | KENT | WA |
| 2015-05-27 | 253-478-7XXX | 7000–7999 | Assigned | CENTURYLINK COMMUNICATIONS, LLC | 508J | KENT | WA |
| 2020-10-20 | 253-478-8XXX | 8000–8999 | Assigned | ONVOY, LLC - WA | 483E | KENT | WA |
| 2016-11-01 | 253-478-9XXX | 9000–9999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC | 6010 | KENT | WA |
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.