NumberResearchThousands-blocks in 310-817
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 310-817 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 310 blocks
Most active assignees, all time — NPA 310
New assignments by month
Sep 2026
Aug 2026
Jul 2026
Jun 2026
May 2026
Apr 2026
Mar 2026
Feb 2026
Jan 2026
Dec 2025
Nov 2025
Oct 2025
| Assigned | Thousands-block | Last 4 digits | Status | Assignee | OCN | Rate center | State |
|---|---|---|---|---|---|---|---|
| 2011-02-28 | 310-817-0XXX | 0000–0999 | Assigned | BANDWIDTH.COM CLEC, LLC - CA | 981E | CMTN GRDN | CA |
| 2006-10-03 | 310-817-1XXX | 1000–1999 | Assigned | T-MOBILE USA, INC. | 6529 | CMTN GRDN | CA |
| 2005-08-18 | 310-817-2XXX | 2000–2999 | Assigned | MCIMETRO ACCESS TRANSMISSION SERVICES LLC | 7229 | CMTN GRDN | CA |
| 2006-10-03 | 310-817-3XXX | 3000–3999 | Assigned | T-MOBILE USA, INC. | 6529 | CMTN GRDN | CA |
| 2006-08-29 | 310-817-4XXX | 4000–4999 | Assigned | TWC IP ENABLED SERVICES, LLC | 793K | CMTN GRDN | CA |
| 2006-08-29 | 310-817-5XXX | 5000–5999 | Assigned | TWC IP ENABLED SERVICES, LLC | 793K | CMTN GRDN | CA |
| 2004-12-21 | 310-817-6XXX | 6000–6999 | Assigned | LEVEL 3 COMMUNICATIONS, LLC - CA | 8826 | CMTN GRDN | CA |
| — | 310-817-7XXX | 7000–7999 | Reserved | PACIFIC BELL | 9740 | CMTN GRDN | CA |
| — | 310-817-8XXX | 8000–8999 | Reserved | PACIFIC BELL | 9740 | CMTN GRDN | CA |
| 2005-06-10 | 310-817-9XXX | 9000–9999 | Assigned | T-MOBILE USA, INC. | 6529 | CMTN GRDN | CA |
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.