| Area Code | 423 |
| State | Tennessee |
| Current Time in Area Code 423 | 423> EDT |
| Timezone | Eastern Daylight Time |
| Regional Market Area | Knoxville Area Metro Chattanooga Tri-Cities Region |
| Metro Area(s) | Athens, TN Chattanooga, TN-GA Cleveland, TN Dayton, TN Greeneville, TN Johnson City, TN Morristown, TN Newport, TN |
| Population (2020) | 1428730 |
| Adjacent Area Codes | 256,276,336,606,706,743,762,828,865,931,938 |
| Chattanooga |
| Cleveland |
| Johnson City |
| Kingsport |