423
Area code
TN
United States geographic area code, in service since 1995-09-11. Part of the 423/729 overlay complex — ten-digit dialing required.
Split from 615. Created 865. Created 729. Overlaid with 729 .
Statusin service
Introduced1995-09-11
JurisdictionTN, US
Local dialing10D
Time zoneEastern / Central
Last verified2026-09-17
Utilization 98.2% of assignable prefixes assigned
As of 09/17/2026
0%778 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 2001-01-09, most recent 2026-09-02.
Area codes serve rate-center geographies, not municipal boundaries. “TN” identifies the jurisdiction, not an exact city footprint.
Top assignees
Ranked by assigned prefixes · initial assignee ≠ current carrier| Rank | Assignee | Prefixes | Share |
|---|---|---|---|
| 01 | BELLSOUTH TELECOMM INC DBA SOUTH CENTRAL BELL TEL | 120 | 15.4% |
| 02 | UNITED TELEPHONE-SOUTHEAST-TN DBA CENTURYLINK - TN | 83 | 10.7% |
| 03 | CELLCO PARTNERSHIP DBA VERIZON WIRELESS - TN | 80 | 10.3% |
| 04 | NEW CINGULAR WIRELESS PCS, LLC - GA | 79 | 10.2% |
| 05 | ONVOY, LLC - TN | 54 | 6.9% |
| 06 | LEVEL 3 COMMUNICATIONS, LLC - TN | 38 | 4.9% |
| 07 | PAETEC ITEL, LLC | 33 | 4.2% |
| 08 | BANDWIDTH.COM CLEC, LLC - TN | 30 | 3.9% |
| 09 | SUNCOM DBA T-MOBILE USA | 24 | 3.1% |
| 10 | POWERTEL ATLANTA LICENSES, INC. | 21 | 2.7% |
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- 2023-07-24 NPA 729 to Overlay NPA 423 (Tennessee)
- 1995-09-11Area code 423 entered service (created from 615).
Planning letters & orders
Primary documents| Date | Document | Subject |
|---|---|---|
| 2024-11-06 | PL-629 ↗ | NPA 729 to Overlay 423 (Tennessee) – supersedes PL-619 |
| 2023-07-24 | PL-619 ↗ | NPA 729 to Overlay NPA 423 (Tennessee) |
| 1999-07-22 | PL-183 ↗ | Geographic Split of 423 (Tennessee) Numbering Plan Area (NPA); addition of 865 NPA |
| 1994-11-22 | IL-94-11-018 ↗ | NANP-SPLIT OF 615 (TENNESSEE) NUMBERING PLAN AREA (NPA) |