Area Code 423: Chattanooga, Tennessee
423 is a telephone area code serving Tennessee, including Chattanooga, Johnson City. It is part of the North American Numbering Plan and is dialed with the country code +1.
Numbers beginning with 423 are located in Tennessee, United States (NANP region: East). The code covers Chattanooga, Johnson City.
How to Dial Area Code 423
| Calling from | What to dial |
|---|---|
| Anywhere in the US or Canada | 1 423 XXX-XXXX (10-digit dialing: 423 + 7-digit number) |
| Local call inside the same area code | 7-digit number in most areas; 10 digits where an overlay code is active |
| From the UK or Europe | 00 1 423 XXX XXXX |
| From Australia | 0011 1 423 XXX XXXX |
| From a mobile phone anywhere | +1 423 XXX XXXX |
Whatever country you are calling from, the + symbol replaces the exit code. Save the contact as +1 423 XXXXXXX and it will dial correctly from any phone in the world.
Time Zone for Area Code 423
Calls to a 423 number ring in the America/New_York time zone, standard offset UTC-05:00. Daylight saving time applies here, so the offset moves forward one hour from March to November.
Note: the Central/Eastern time zone line runs through this area code - its western edge follows the eastern borders of Marion and Sequatchie counties, so Chattanooga and Johnson City are on Eastern time.
Cities and Communities Served by 423
The following places fall inside the 423 calling area:
Other Area Codes in Tennessee
These codes also serve Tennessee. Area codes are assigned by the North American Numbering Plan Administration (NANPA).
| Area Code | Cities / Coverage |
|---|---|
| 615 | Nashville |
| 629 | Nashville (overlay) |
| 731 | Jackson |
| 865 | Knoxville |
| 901 | Memphis |
| 931 | Clarksville, Cookeville |
See all 7 area codes in Tennessee →
Frequently Asked Questions
Where is area code 423?
Area code 423 is in Tennessee, United States. It covers Chattanooga, Johnson City.
What time zone is area code 423 in?
Area code 423 rings in the America/New_York time zone (UTC-05:00 standard).
Do I need to dial 1 before area code 423?
Yes, for a long-distance call inside the US and Canada you dial 1 first, then 423, then the seven-digit number. The 1 is the North American long-distance trunk prefix — it is not the country code. From outside North America you dial your exit code then 1 then 423.
Is area code 423 toll-free?
No. 423 is a standard geographic area code, so normal long-distance rates apply unless your plan includes them. Toll-free NANP codes are 800, 833, 844, 855, 866, 877 and 888.