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 |
|---|---|---|---|---|---|---|
| — | 406-323 | none assigned yet which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | ROUNDUP | MT |
| — | 406-354 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | ROCK SPG | MT |
| — | 406-358 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | MELSTONE | MT |
| — | 406-428 | 8XXX which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | GRASSRANGE | MT |
| — | 406-429 | 8XXX which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | WINNETT | MT |
| — | 406-464 | 4XXX6XXX · 2 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | ROY | MT |
| — | 406-485 | 5XXX8XXX · 2 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | CIRCLE | MT |
| — | 406-486 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | FALLON | MT |
| — | 406-525 | 2XXX5XXX · 2 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | SO WOLF PT | MT |
| — | 406-557 | 1XXX3XXX7XXX · 3 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | JORDAN | MT |
| — | 406-568 | 4XXX which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | RYEGATE | MT |
| — | 406-575 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | NO RYEGATE | MT |
| — | 406-583 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | BLOOMFIELD | MT |
| — | 406-584 | none assigned yet which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | LINDSAY | MT |
| — | 406-588 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | CARLYLE | MT |
| — | 406-635 | 0XXX1XXX2XXX3XXX6XXX7XXX8XXX · 5 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | TERRY | MT |
| — | 406-636 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | LAVINA | MT |
| — | 406-687 | 0XXX2XXX4XXX which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | W GLENDIVE | MT |
| — | 406-772 | 1XXX2XXX7XXX · 2 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | PLEVNA | MT |
| — | 406-773 | 3XXX7XXX · 2 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | RICHEY | MT |
| — | 406-774 | 1XXX4XXX · 2 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | LAMBERT | MT |
| — | 406-775 | 1XXX4XXX5XXX7XXX · 3 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | EKALAKA | MT |
| — | 406-776 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | SAVAGE | MT |
| — | 406-778 | 1XXX4XXX · 2 holders which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | BAKER | MT |
| — | 406-798 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | WESTSIDNEY | MT |
| — | 406-856 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | CUSTER | MT |
| — | 406-947 | not yet reported which blocks → | MID-RIVERS TEL. COOP., INC. | 2246 | MUSSELSHLL | MT |
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.