NumberResearchRecent prefix assignments
0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/20/2026
The Code holder is who opened each NPA-NXX prefix — not necessarily who holds the numbers. A prefix is 10,000 numbers, but under pooling its ten 1,000-number blocks are handed out individually, often to different carriers; the code holder may hold only one block, or none. The Thousands-blocks column shows how the ten blocks are really split — click which blocks → to see who holds each 1,000-number block and its last-4-digit range. Assignments are initial assignments; the current serving carrier may differ due to portability.
| Assigned | NPA-NXX | Thousands-blocks taken (last-4 opening) | Code holder | OCN | Rate center | State |
|---|---|---|---|---|---|---|
| 2010-10-21 | 321-400 | 0–9 XXXall 10 · 3 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | ORLANDO | FL |
| 2005-12-29 | 321-445 | 0–9 XXXall 10 · 4 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | ORLANDO | FL |
| 2004-03-19 | 321-293 | 0–9 XXXwhole prefix which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | ORLANDO | FL |
| — | 321-251 | 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | ORLANDO | FL |
| — | 321-282 | 2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 3 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | WINTERPARK | FL |
| — | 321-283 | 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 4 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | SANFORD | FL |
| — | 321-284 | 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | KISSIMMEE | FL |
| — | 321-286 | 2XXX3XXX4XXX6XXX7XXX8XXX · 4 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | WKISSIMMEE | FL |
| — | 321-296 | 2XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | OVIEDO | FL |
| — | 321-354 | 4XXX5XXX7XXX8XXX which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | ORLANDO | FL |
| — | 321-574 | 1XXX2XXX4XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → | MCI WORLDCOM COMMUNICATIONS, INC. - FL | 7448 | MELBOURNE | FL |
Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/20/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.