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

ALTA prefixes in area code 530

NANPA records 4 assigned NXX blocks to rate center ALTA in area code 530, 0.5% of the 782 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 TELEPORT COMMUNICATIONS AMERICA, LLC - CA (1), PACIFIC BELL (1), ONVOY, LLC - CA (1). The earliest assignment on record here is 2011-12-08 and the most recent 2011-12-08. 4 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 307, 385, 406, 712 – overlay codes cover the same geography, so a rate center is served by all of them.

4 assigned blocks – 0.5% of 530
4 holders of record
4 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
530-388 AT&T TELEPORT COMMUNICATIONS AMERICA, LLC - CA – yes yes
530-389 AT&T PACIFIC BELL – yes yes
530-464 Onvoy ONVOY, LLC - CA – yes yes
530-847 AT&T AT&T ENTERPRISES, LLC 2011-12-08 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
TELEPORT COMMUNICATIONS AMERICA, LLC - CA AT&T 1 25%
PACIFIC BELL AT&T 1 25%
ONVOY, LLC - CA Onvoy 1 25%
AT&T ENTERPRISES, LLC AT&T 1 25%

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 ALTA in area code 530?

4 blocks: 388, 389, 464, 847. The table above gives the holder of each.

Which carriers have numbers in ALTA?

TELEPORT COMMUNICATIONS AMERICA, LLC - CA (1 block), PACIFIC BELL (1 block), ONVOY, LLC - CA (1 block), AT&T ENTERPRISES, 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 ALTA 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 530

All 782 prefixes in 530