🇺🇸 423 area code
Area code 423 covers Chattanooga, Johnson City, Kingsport and Cleveland and the surrounding area in Tennessee. It shares that territory with 729, so the same neighbourhood can have numbers in any of them. Enter a 423 number below for a free check before you call back.
- Location: Chattanooga, Tennessee
- Time zone: Eastern and Central (UTC−6)
- In service since September 11, 1995
Look up a number
Validity, carrier, line type, and region on the first pass.
Area code 423 at a glance
- Area code
- 423
- Location
- Tennessee, United States
- Main cities
- Chattanooga, Johnson City, Kingsport, Cleveland, Morristown, Bristol
- Time zone
- Eastern and Central (UTC−6)
- Local time now
- —
- In service since
- September 11, 1995
- Created from
- 615
- Overlay codes
- 729
- Codes split from it
- 729, 865
- Local calls
- Dial 10 digits
- Number format
- (423) 555-0123
- From abroad
- +1 423 555 0123
Cities in area code 423
- Chattanooga
- Johnson City
- Kingsport
- Cleveland
- Morristown
- Bristol
- Greeneville
- Athens
- Elizabethton
- Hixson
Is a 423 call a scam?
An area code tells you where a number was first assigned, not where the caller is. Mobile numbers keep their area code when people move, and internet (VoIP) numbers can be picked in any area code — so a 423 number can be calling from anywhere.
Robocallers exploit that with "neighbor spoofing": showing a 423 number to people in Tennessee because a local-looking call is more likely to be answered. If a 423 call claims to be your bank, the IRS or a delivery company, hang up and call the official number yourself.
About area code 423
423 entered service on September 11, 1995, when it was split from 615.
It is part of the 423/729 overlay: the codes cover the same area, and a new line there can be given a number in any of them. Two neighbours — or two phones in one household — can have different area codes. That is also why local calls need the full ten digits.
As the region grew, 729 and 865 were carved out of or added to 423.
The area straddles a time-zone line (Eastern and Central), so a 423 caller may be an hour ahead of or behind the next town.
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FAQ
Area code 423 questions
Sources: NANPA NPA database (11/04/2026) and Google libphonenumber. Area codes show where a number was assigned, not where its owner is today.
Where is area code 423?
Area code 423 is in Tennessee, United States. It covers Chattanooga, Johnson City, Kingsport, Cleveland, Morristown and Bristol.
What time zone is area code 423?
423 is in the Eastern and Central (UTC−6) time zone, and observes daylight saving time.
What area codes overlay 423?
729 serves the same area as 423. Numbers in all of them are local to one another.
When did area code 423 start?
423 entered service on September 11, 1995, created from 615.
How do I find out who called me from 423?
Enter the full number in the lookup at the top of this page. The free check confirms whether the number is valid and shows its carrier, line type and region; a full report adds owner and public-web records where they are available.
Why am I getting calls from area code 423?
If you live in or near Tennessee, they may be genuinely local — or robocalls spoofing a local-looking number. Unknown 423 callers who will not leave a message are best looked up before you call back.
Got a call from 423?
Run the free check first — validity, carrier, line type and region — and unlock the full report only if you need it.