512
Area code
TX
United States geographic area code, in service since 1947-01-01. Part of the 512/737 overlay complex — ten-digit dialing required.
Statusin service
Introduced1947-01-01
JurisdictionTX, US
Local dialing10D
Time zoneCentral
Last verified2026-09-17
Utilization 101% of assignable prefixes assigned
As of 09/17/2026
0%800 of ~792 assignable NXX values (200–999 excl. N11)100%
Prefix-level assignment does not equal number-level exhaustion; thousands-block pooling extends capacity. First assignment on record 2001-01-08, most recent 2024-11-01.
Area codes serve rate-center geographies, not municipal boundaries. “TX” identifies the jurisdiction, not an exact city footprint.
Top assignees
Ranked by assigned prefixes · initial assignee ≠ current carrier| Rank | Assignee | Prefixes | Share |
|---|---|---|---|
| 01 | SOUTHWESTERN BELL | 274 | 34.3% |
| 02 | NEW CINGULAR WIRELESS PCS, LLC - IL | 98 | 12.3% |
| 03 | T-MOBILE USA, INC. | 70 | 8.8% |
| 04 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TX | 49 | 6.1% |
| 05 | LEVEL 3 OF TELECOM OF TEXAS, LLC - TX | 45 | 5.6% |
| 06 | FRONTIER SOUTHWEST INC DBA FRONTIER COMM OF TEXAS | 37 | 4.6% |
| 07 | ONVOY, LLC - TX | 25 | 3.1% |
| 08 | LEVEL 3 COMMUNICATIONS, LLC - TX | 21 | 2.6% |
| 09 | BANDWIDTH.COM CLEC, LLC - TX | 17 | 2.1% |
| 10 | TELEPORT COMMUNICATIONS AMERICA, LLC - TX | 16 | 2% |
Important: these are initial assignees from NANPA CO-code records — the carrier a prefix was originally assigned to. Because of number portability, the current serving carrier of any individual number may differ.
Change history
Recorded events for this NPA- 2012-08-01 NPA 737 to Overlay NPA 512 (Texas)
- 1947-01-01Area code 512 entered service.
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2012-08-01 | PL-438 ↗ | NPA 737 to Overlay NPA 512 (Texas) |
| 2000-07-05 | PL-233 ↗ | NPA 737 to Overlay NPA 512 (Texas) |
| 1999-02-23 | PL-158 ↗ | Update of Jeopardy Procedures for Numbering Plan Area (NPA) 512 in Texas; this notice updates PL-099 |
| 1992-03-01 | IL-92-03-068 ↗ | NANP-SPLIT OF 512 (SOUTH TEXAS) NUMBERING PLAN AREA (NPA) |