NumberingData
Verified Nov 1, 2026 · Source: NANPA CO Code Assignment Records

SIDNEY prefixes in area code 406

NANPA records 9 assigned NXX blocks to rate center SIDNEY in area code 406, 1.2% of the 754 blocks assigned in the code. A rate center is the billing geography a block is allocated to – NANPA truncates the name to ten characters, so read it as a NANPA label rather than a town. 5 holders hold those blocks, the largest being CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT (3), MID-RIVERS TELEPHONE COOPERATIVE, INC. (2), LEVEL 3 COMMUNICATIONS, LLC - MT (2). The earliest assignment on record here is 2003-01-09 and the most recent 2005-02-16. 7 of them are in thousands-block pooling, so those prefixes are shared between carriers in 1,000-number lots. The same rate center name also appears in area codes 207, 217, 252, 254 – overlay codes cover the same geography, so a rate center is served by all of them.

9 assigned blocks – 1.2% of 406
5 holders of record
7 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
406-433 MID-RIVERS TELEPHONE COOPERATIVE, INC. – no yes
406-478 Verizon CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT – yes yes
406-480 Verizon CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT – yes yes
406-482 Lumen QWEST CORPORATION – yes yes
406-488 MID-RIVERS TELEPHONE COOPERATIVE, INC. – no yes
406-489 AT&T NEW CINGULAR WIRELESS PCS, LLC – yes yes
406-630 Lumen LEVEL 3 COMMUNICATIONS, LLC - MT 2005-02-16 yes yes
406-943 Lumen LEVEL 3 COMMUNICATIONS, LLC - MT 2003-01-09 yes yes
406-973 Verizon CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT – yes yes

The holder is who received the block from the numbering administrator. It is not necessarily the carrier serving a given number: numbers move with their owners, and a pooled block is shared.

Who holds the blocks

HolderBrandBlocksShare here
CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT Verizon 3 33.3%
MID-RIVERS TELEPHONE COOPERATIVE, INC. – 2 22.2%
LEVEL 3 COMMUNICATIONS, LLC - MT Lumen 2 22.2%
QWEST CORPORATION Lumen 1 11.1%
NEW CINGULAR WIRELESS PCS, LLC AT&T 1 11.1%

Same rate center in other codes

Overlay codes cover the same geography, so one rate center is served by all of them.

Frequently asked

Which prefixes belong to SIDNEY in area code 406?

9 blocks: 433, 478, 480, 482, 488, 489, 630, 943, 973. The table above gives the holder of each.

Which carriers have numbers in SIDNEY?

CELLCO PARTNERSHIP DBA VERIZON WIRELESS - MT (3 blocks), MID-RIVERS TELEPHONE COOPERATIVE, INC. (2 blocks), LEVEL 3 COMMUNICATIONS, LLC - MT (2 blocks), QWEST CORPORATION (1 block), NEW CINGULAR WIRELESS PCS, LLC (1 block). These are the holders on record; the carrier actually serving a given number can differ, because numbers move with their owners.

Is SIDNEY a city?

It is a rate center – the unit NANPA allocates number blocks to. Its name is abbreviated to ten characters and is not necessarily a settlement: we print it as recorded rather than guess at the full name.

Other rate centers in 406

All 754 prefixes in 406