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

ALANSON prefixes in area code 231

NANPA records 4 assigned NXX blocks to rate center ALANSON 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 NEW CINGULAR WIRELESS PCS, LLC - IL (1), INTERACTIVE SERVICES NETWORK, INC. (1), ONVOY, LLCV - MI (1). The earliest assignment on record here is 2004-03-19 and the most recent 2019-10-10. 2 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
2 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
231-203 AT&T NEW CINGULAR WIRELESS PCS, LLC - IL 2004-03-19 yes yes
231-243 INTERACTIVE SERVICES NETWORK, INC. 2004-03-24 no yes
231-400 Onvoy ONVOY, LLCV - MI 2019-10-10 yes yes
231-548 Brightspeed BRIGHTSPEED OF MICHIGAN, LLC – no 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
NEW CINGULAR WIRELESS PCS, LLC - IL AT&T 1 25%
INTERACTIVE SERVICES NETWORK, INC. – 1 25%
ONVOY, LLCV - MI Onvoy 1 25%
BRIGHTSPEED OF MICHIGAN, LLC Brightspeed 1 25%

Frequently asked

Which prefixes belong to ALANSON in area code 231?

4 blocks: 203, 243, 400, 548. The table above gives the holder of each.

Which carriers have numbers in ALANSON?

NEW CINGULAR WIRELESS PCS, LLC - IL (1 block), INTERACTIVE SERVICES NETWORK, INC. (1 block), ONVOY, LLCV - MI (1 block), BRIGHTSPEED OF MICHIGAN, 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 ALANSON 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