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 |
|---|---|---|---|---|---|---|
| 2023-04-06 | 423-841 | 0XXX3XXX8XXX9XXX · 3 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | MOUNTAINCY | TN |
| 2012-05-24 | 423-518 | 0–9 XXXall 10 · 6 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | ELIZABTHTN | TN |
| 2004-09-29 | 423-557 | 0–9 XXXall 10 · 2 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | JOHNSON CY | TN |
| 2002-03-22 | 423-388 | 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 3 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | ERWIN | TN |
| 2001-11-14 | 423-383 | not yet reported which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | BRISTOL | TN |
| 2001-11-14 | 423-384 | not yet reported which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | FALLBRANCH | TN |
| 2001-11-07 | 423-213 | 0XXX1XXX2XXX3XXX4XXX5XXX6XXX7XXX · 3 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | ELIZABTHTN | TN |
| 2001-08-31 | 423-291 | 0XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 4 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | MOUNTAINCY | TN |
| 2001-03-09 | 423-946 | 0XXX1XXX2XXX3XXX4XXX5XXX6XXX · 2 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | JOHNSON CY | TN |
| 2001-02-09 | 423-773 | not yet reported which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | JOHNSON CY | TN |
| — | 423-292 | not yet reported which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | FALLBRANCH | TN |
| — | 423-340 | 3XXX4XXX5XXX7XXX8XXX9XXX · 4 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | BRISTOL | TN |
| — | 423-646 | 0XXX which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | BRISTOL | TN |
| — | 423-647 | 0XXX which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | BUTLER | TN |
| — | 423-676 | 0XXX which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | JOHNSON CY | TN |
| — | 423-677 | 4XXX which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | FALLBRANCH | TN |
| — | 423-791 | 7XXX8XXX9XXX · 2 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | JOHNSON CY | TN |
| — | 423-823 | 3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 5 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | GREENEVL | TN |
| — | 423-833 | 0–9 XXXall 10 · 3 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | JOHNSON CY | TN |
| — | 423-895 | 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX9XXX · 2 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | ELIZABTHTN | TN |
| — | 423-943 | none assigned yet which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | JOHNSON CY | TN |
| — | 423-948 | 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | LIMESTONE | TN |
| — | 423-957 | 2XXX3XXX4XXX5XXX7XXX8XXX · 4 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | HAMPTON | TN |
| — | 423-972 | 1XXX2XXX3XXX4XXX5XXX6XXX7XXX8XXX · 3 holders which blocks → | SUNCOM DBA T-MOBILE USA | 8645 | GREENEVL | TN |
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.