NumberResearchRecent prefix assignments
0 prefixes assigned in the last 30 days · from the daily NANPA CO code file, 09/19/2026
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 |
|---|---|---|---|---|---|---|
| 2011-10-07 | 443-917 | 0–9 XXXall 10 · 8 holders which blocks → | ONVOY, LLC - MD | 876D | COLUMBIA | MD |
| 2010-02-23 | 443-873 | 0–9 XXXall 10 · 5 holders which blocks → | ONVOY, LLC - MD | 876D | BALTIMORE | MD |
| 2007-10-12 | 443-453 | 0–9 XXXall 10 · 4 holders which blocks → | ONVOY, LLC - MD | 876D | BALTIMORE | MD |
| — | 443-222 | 0–9 XXXall 10 · 2 holders which blocks → | ONVOY, LLC - MD | 876D | WORTHINGTN | MD |
| — | 443-241 | not yet reported which blocks → | ONVOY, LLC - MD | 876D | WESTMINSTR | MD |
| — | 443-251 | 0–9 XXXall 10 · 5 holders which blocks → | ONVOY, LLC - MD | 876D | CATONSVL | MD |
| — | 443-399 | 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → | ONVOY, LLC - MD | 876D | DUNDALK | MD |
| — | 443-491 | 2XXX3XXX7XXX8XXX9XXX · 5 holders which blocks → | ONVOY, LLC - MD | 876D | PARKTON | MD |
| — | 443-516 | 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 6 holders which blocks → | ONVOY, LLC - MD | 876D | SYKESVILLE | MD |
| — | 443-581 | 0–9 XXXall 10 · 5 holders which blocks → | ONVOY, LLC - MD | 876D | CHASE | MD |
| — | 443-658 | not yet reported which blocks → | ONVOY, LLC - MD | 876D | WOODLAWN | MD |
| — | 443-659 | not yet reported which blocks → | ONVOY, LLC - MD | 876D | WEST RIVER | MD |
| — | 443-781 | 0–9 XXXall 10 · 5 holders which blocks → | ONVOY, LLC - MD | 876D | ARGRGBSNIS | MD |
| — | 443-785 | not yet reported which blocks → | ONVOY, LLC - MD | 876D | ARBUTUS | MD |
Source: NANPA CO Code Assignments (Utilized, All States, Public), file date 09/19/2026 — Tier A primary source, refreshed on every import. Viewing is free; bulk downloads require a membership.