423 area code
Area code 423 is in Tennessee. It covers Chattanooga, Johnson City, Kingsport and 165 other places: 172 ZIP codes in Hamilton, Sullivan, Washington and 22 other counties. It spans two time zones: local time there is Eastern or Central. In service since 1995; 729 (2025) overlays it, so a number from there can have either code.
- State
- Tennessee
- Time zone
- Eastern and Central
- Largest city
- Chattanooga
- Overlays
- 729
- In service since
- 1995
- Rate centres
- 75
- Prefixes assigned
- 764 (7,640,000 numbers)
Who calls from a 423 number
NANPA records the carrier each block of 423 numbers is assigned to. Of the 7.1 million 423 numbers assigned, 38% are with mobile carriers (Verizon Wireless, AT&T Mobility and T-Mobile); 33% with cable, internet-calling, business and other carriers (Onvoy); 28% with local phone companies (AT&T and CenturyLink).
That is who the numbers were assigned to: people keep their number when they change carrier, so any one number may have moved since.
| Carrier | Kind | Share |
|---|---|---|
| Verizon Wireless | Mobile | 16% |
| AT&T | Landline | 14% |
| AT&T Mobility | Mobile | 12% |
| Onvoy | Cable, VoIP, other | 11% |
| CenturyLink | Landline | 10% |
| T-Mobile | Mobile | 9% |
An area code says where a number was issued, not where the caller is: people keep their numbers when they move, and caller ID can be set to show any number, which the FCC calls spoofing. If a call you did not expect asks for money or personal details, the FCC advises hanging up and calling the company back on a number you look up yourself. Unwanted calls can be reported to the FTC at ReportFraud.ftc.gov.
Places in area code 423
The 63 places with a telephone rate centre of their own using 423, largest first. Each links to its ZIP codes.
Nearby places using 423
These places have no rate centre of their own in NANPA's records; the nearest one uses 423. Near an area-code boundary that can be wrong for part of a town.
- Hixson
- East Ridge
- Middle Valley
- Red Bank
- Chuckey
- Piney Flats
- Bloomingdale
- Signal Mountain
- Harrison
- South Cleveland
- Jonesborough
- Afton
- Mount Carmel
- Mc Donald
- Oak Grove
- Harrogate
- Spurgeon
- Unicoi
- Whitesburg
- Wildwood Lake
- Old Fort
- Tusculum
- Colonial Heights
- Birchwood
- Sale Creek
- Tazewell
- Lancing
- Hopewell
- Pioneer
- Walnut Hill
- Falling Water
- Gray
- Lakesite
- Valley Forge
- Lookout Mountain
- Fairmount
- Pine Crest
- Central
- Del Rio
- East Cleveland
- Hunter
- Biltmore
- Walden
- Mohawk
- Evensville
- Mowbray Mountain
- Kimball
- Turtletown
- Powells Crossroads
- Lone Oak
- Fincastle
- Graysville
- Duff
- Grandview
- Banner Hill
- Winfield
- Tellico Plains
- Embreeville
- Flag Pond
- Flat Top Mountain
ZIP codes in area code 423
172 ZIP codes in 126 towns, by the town each is mailed to, largest first. Each links to its own page.
Where 423 numbers are issued
NANPA's rate centres with the most 423 prefixes (each prefix is 10,000 numbers), under NANPA's own abbreviated names.
| Rate centre | Place | Prefixes |
|---|---|---|
CHATTNOOGA | Chattanooga | 183 |
JOHNSON CY | Johnson City | 67 |
BRISTOL | Bristol | 38 |
CLEVELAND | Cleveland | 33 |
KINGSPORT | Kingsport | 32 |
MORRISTOWN | Morristown | 28 |
Counties
The counties of its ZIP codes, most residents first, with how many of its ZIP codes each has.
- Hamilton County (32)
- Sullivan County (13)
- Washington County (11)
- Bradley County (7)
- Greene County (8)
- Hamblen County (7)
- Hawkins County (6)
- McMinn County (7)
- Marion County (7)
- Monroe County (5)
- Carter County (6)
- Cocke County (6)
- Rhea County (4)
- Claiborne County (10)
- Campbell County (5)
- Scott County (6)
- Johnson County (5)
- Polk County (10)
- Unicoi County (3)
- Morgan County (7)
- Bledsoe County (2)
- Sequatchie County (1)
- Meigs County (1)
- Hancock County (2)
- Grundy County (1)
Which code covers where you are now? What area code am I in? answers from your location.
Questions about area code 423
Where is area code 423?
Area code 423 is in Tennessee. It covers Chattanooga, Johnson City, Kingsport and 165 other places: 172 ZIP codes in Hamilton, Sullivan, Washington and 22 other counties.
What ZIP codes are in area code 423?
172 ZIP codes, by the town each is mailed to: Chattanooga (20, 37401 to 37450), Johnson City (6, 37601 to 37615), Kingsport (6, 37660 to 37669), Cleveland (5, 37311 to 37364) and 122 more towns. The full list is on this page.
What time zone is area code 423 in?
Eastern and Central time.
Is a 423 number a mobile or a landline?
It can be either. 38% of 423 numbers are assigned to mobile carriers and 28% to local phone companies (NANPA, 2026-10-10); the rest are with cable, internet-calling, business and paging carriers. A number keeps its area code when it moves to another carrier.
What area codes overlay 423?
729. They cover the same area as 423, so a new number there can be given any of them.
Does a 423 number mean the caller is in Tennessee?
Not necessarily. An area code says where the number was first issued. People keep their numbers when they move or switch carriers, and calling software can show any number, so a 423 call can come from anywhere.
Other area codes in Tennessee
All 8 Tennessee area codes, by area, with the cities each covers
Source: NANPA NPA database, central office code and thousands-block assignments, 2026-10-10. Places are matched to NANPA's rate centres by name; see sources.
Cite this page
zipcodes.pro. “Area code 423.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/area-code/423
Underlying data is public domain or openly licensed — sources, vintages and licences.