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

ONEKAMA prefixes in area code 231

NANPA records 4 assigned NXX blocks to rate center ONEKAMA in area code 231, 0.7% of the 572 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. 4 holders hold those blocks, the largest being SPOK, INC. (1), BANDWIDTH.COM CLEC, LLC - MI (1), KALEVA TELEPHONE COMPANY - MI (1). The earliest assignment on record here is 2008-06-03 and the most recent 2021-08-26. 3 of them are in thousands-block pooling, so those prefixes are shared between carriers in 1,000-number lots.

4 assigned blocks – 0.7% of 231
4 holders of record
3 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
231-255 Spok SPOK, INC. – no yes
231-379 Bandwidth BANDWIDTH.COM CLEC, LLC - MI 2021-08-26 yes yes
231-508 KALEVA TELEPHONE COMPANY - MI 2008-06-03 yes yes
231-889 AT&T MICHIGAN BELL TEL CO – 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
SPOK, INC. Spok 1 25%
BANDWIDTH.COM CLEC, LLC - MI Bandwidth 1 25%
KALEVA TELEPHONE COMPANY - MI – 1 25%
MICHIGAN BELL TEL CO AT&T 1 25%

Frequently asked

Which prefixes belong to ONEKAMA in area code 231?

4 blocks: 255, 379, 508, 889. The table above gives the holder of each.

Which carriers have numbers in ONEKAMA?

SPOK, INC. (1 block), BANDWIDTH.COM CLEC, LLC - MI (1 block), KALEVA TELEPHONE COMPANY - MI (1 block), MICHIGAN BELL TEL CO (1 block). These are the holders on record; the carrier actually serving a given number can differ, because numbers move with their owners.

Is ONEKAMA 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 231

All 572 prefixes in 231