NumberResearchThousands-blocks in 858-228
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 858-228 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 858 blocks
Most active assignees, last 30 days — NPA 858
New assignments by month
Sep 2026
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2004-05-19 | 858-228-0XXX | 0000–0999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC | 6010 | LA JOLLA | CA |
| — | 858-228-1XXX | 1000–1999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA | 7240 | LA JOLLA | CA |
| — | 858-228-2XXX | 2000–2999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA | 7240 | LA JOLLA | CA |
| — | 858-228-3XXX | 3000–3999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA | 7240 | LA JOLLA | CA |
| — | 858-228-4XXX | 4000–4999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA | 7240 | LA JOLLA | CA |
| — | 858-228-5XXX | 5000–5999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA | 7240 | LA JOLLA | CA |
| 2003-10-16 | 858-228-6XXX | 6000–6999 | Assigned | NEW CINGULAR WIRELESS PCS, LLC | 6010 | LA JOLLA | CA |
| 2005-02-17 | 858-228-7XXX | 7000–7999 | Assigned | T-MOBILE USA, INC. | 6529 | LA JOLLA | CA |
| 2026-09-03 | 858-228-8XXX | 8000–8999 | Assigned | ONVOY, LLC - CA | 649C | LA JOLLA | CA |
| — | 858-228-9XXX | 9000–9999 | Reserved | MCIMETRO ACCESS TRANSMISSION SERVICES LLC - CA | 7240 | LA JOLLA | CA |
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.