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

BERTRAM prefixes in area code 512

NANPA records 3 assigned NXX blocks to rate center BERTRAM in area code 512, 0.4% of the 785 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. 3 holders hold those blocks, the largest being TELNYX LLC (1), FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS (1), ONVOY, LLC - TX (1). The earliest assignment on record here is 2014-06-18 and the most recent 2014-06-18. 3 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 code 737 – overlay codes cover the same geography, so a rate center is served by all of them.

3 assigned blocks – 0.4% of 512
3 holders of record
3 of them pooled in 1,000-number lots

Prefixes assigned here

PrefixHolder of recordAssignedPooledIn service
512-277 Telnyx TELNYX LLC – yes yes
512-355 Frontier FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS – yes yes
512-572 Onvoy ONVOY, LLC - TX 2014-06-18 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
TELNYX LLC Telnyx 1 33.3%
FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS Frontier 1 33.3%
ONVOY, LLC - TX Onvoy 1 33.3%

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 BERTRAM in area code 512?

3 blocks: 277, 355, 572. The table above gives the holder of each.

Which carriers have numbers in BERTRAM?

TELNYX LLC (1 block), FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS (1 block), ONVOY, LLC - TX (1 block). These are the holders on record; the carrier actually serving a given number can differ, because numbers move with their owners.

Is BERTRAM 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 512

All 785 prefixes in 512