NumberResearchThousands-blocks in 857-336
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 857-336 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 857 blocks
Most active assignees, all time — NPA 857
New assignments by month
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Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2016-03-02 | 857-336-0XXX | 0000–0999 | Assigned | ONVOY, LLC - MA | 892D | WINTHROP | MA |
| 2016-03-02 | 857-336-1XXX | 1000–1999 | Assigned | ONVOY, LLC - MA | 892D | WINTHROP | MA |
| 2016-03-18 | 857-336-2XXX | 2000–2999 | Assigned | HD CARRIER LLC | 321J | WINTHROP | MA |
| 2016-03-18 | 857-336-3XXX | 3000–3999 | Assigned | HD CARRIER LLC | 321J | WINTHROP | MA |
| 2016-03-18 | 857-336-4XXX | 4000–4999 | Assigned | HD CARRIER LLC | 321J | WINTHROP | MA |
| 2016-03-18 | 857-336-5XXX | 5000–5999 | Assigned | HD CARRIER LLC | 321J | WINTHROP | MA |
| 2016-06-17 | 857-336-6XXX | 6000–6999 | Assigned | BANDWIDTH.COM CLEC, LLC - MA | 990E | WINTHROP | MA |
| — | 857-336-7XXX | 7000–7999 | Available | WINTHROP | MA | ||
| 2016-06-01 | 857-336-8XXX | 8000–8999 | Assigned | IP HORIZON LLC | 515J | WINTHROP | MA |
| 2016-08-10 | 857-336-9XXX | 9000–9999 | Assigned | HD CARRIER LLC | 321J | WINTHROP | 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.