NumberResearchThousands-blocks in 831-574
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 831-574 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 831 blocks
Most active assignees, all time — NPA 831
New assignments by month
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| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| — | 831-574-0XXX | 0000–0999 | Reserved | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | CARMEL | CA |
| 2015-06-29 | 831-574-1XXX | 1000–1999 | Assigned | BANDWIDTH.COM CLEC, LLC - CA | 981E | CARMEL | CA |
| 2017-04-14 | 831-574-2XXX | 2000–2999 | Assigned | ONVOY, LLC - CA | 649C | CARMEL | CA |
| 2008-05-07 | 831-574-3XXX | 3000–3999 | Assigned | AT&T ENTERPRISES, LLC | 516C | CARMEL | CA |
| 2013-01-22 | 831-574-4XXX | 4000–4999 | Assigned | U.S. TELEPACIFIC CORP. DBA TPX COMMUNICATIONS | 671J | CARMEL | CA |
| 2011-12-07 | 831-574-5XXX | 5000–5999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | CARMEL | CA |
| 2007-10-08 | 831-574-6XXX | 6000–6999 | Assigned | ONVOY, LLC - CA | 649C | CARMEL | CA |
| 2015-09-16 | 831-574-7XXX | 7000–7999 | Assigned | CENTURYLINK COMMUNICATIONS, LLC | 508J | CARMEL | CA |
| 2015-07-15 | 831-574-8XXX | 8000–8999 | Assigned | COMCAST PHONE OF CALIFORNIA, LLC | 394L | CARMEL | CA |
| 2016-06-22 | 831-574-9XXX | 9000–9999 | Assigned | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CA | 6006 | CARMEL | 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.