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 |
|---|---|---|---|---|---|---|
| — | 410-369 | 6XXX8XXX which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | BALTIMORE | MD |
| — | 410-565 | 2XXX5XXX6XXX8XXX · 4 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | ARBUTUS | MD |
| — | 410-589 | 0XXX2XXX3XXX5XXX6XXX · 3 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | BRYNPKLNCM | MD |
| — | 410-595 | 1XXX2XXX5XXX6XXX · 3 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | GLENBURNIE | MD |
| — | 410-680 | 2XXX3XXX6XXX8XXX · 3 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | ELLICOTTCY | MD |
| — | 410-717 | 2XXX3XXX5XXX6XXX8XXX · 2 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | ELKRIDGE | MD |
| — | 410-794 | 5XXX6XXX · 2 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | COLUMBIA | MD |
| — | 410-807 | 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 4 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | CATONSVL | MD |
| — | 410-824 | 0XXX1XXX2XXX3XXX4XXX5XXX6XXX8XXX9XXX · 8 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | WATERLO236 | MD |
| — | 410-921 | 0XXX1XXX2XXX3XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | SEVERN | MD |
| — | 410-927 | 1XXX3XXX5XXX6XXX8XXX · 2 holders which blocks → | LEVEL 3 TELECOM OF MARYLAND, LLC - MD | 7591 | ODENTON | MD |
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.