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423 Area Code

Area code 423 serves Chattanooga, Johnson City, Kingsport, Cleveland, Morristown and nearby communities in Tennessee. It has been in service since September 11, 1995, when it was split from 615.

StateTennessee
Time zonesEastern / Central
Local time now…
Prefixes in use764
Overlay with729
Projected to run out2081
ChattanoogaJohnson CityKingsportClevelandMorristownBristolEast RidgeGreenevilleAthensElizabethtonSoddy-DaisyRed BankMiddle ValleyCollegedaleBloomingdaleSignal MountainHarrisonDaytonSouth ClevelandChurch HillLa FolletteNewportJonesboroughSweetwaterDunlapErwinMount CarmelMadisonvilleChattanoogaJohnson CityKingsportClevelandMorristownAthens
Cities and towns served by area code 423

Who issues 423 numbers

Mobile 31%VoIP and cable 24%Landline 45%

Share of the 764 prefixes (the three digits after 423) assigned to each type of carrier. Classification by carrier name, approximate.

CarrierPrefixes
South Central Bell Tel119
Lumen (CenturyLink)85
AT&T Mobility80
Verizon Wireless80
T-Mobile64
Onvoy (Sinch)58
Lumen (Level 3)38
Paetec Itel33

Cities and towns in area code 423

CityPopulationOther area codes
Chattanooga194,144
Johnson City74,943
Kingsport57,530
Cleveland51,172
Morristown33,517
Bristol28,107
East Ridge21,921
Greeneville16,141
Athens15,263
Elizabethton14,350
Soddy-Daisy13,474
Red Bank12,405
Middle Valley11,808
Collegedale11,499
Bloomingdale8,840
Signal Mountain8,824
Harrison8,446
Dayton7,819
South Cleveland7,748
Church Hill7,297
La Follette7,176
Newport7,049
Jonesborough6,990
Sweetwater6,706
Dunlap6,089
Erwin6,019
Mount Carmel5,540
Madisonville5,428

Got a call from 423?

A 423 number was originally issued in Tennessee, but that does not prove the caller is there. 24% of 423 prefixes belong to VoIP and cable providers, whose numbers can be bought online and used from anywhere. Caller ID can also be spoofed, so treat urgent requests for money, codes or passwords from any area code with suspicion, and call back on a number you already know.

All 764 prefixes in area code 423

Format: (423) XXX-YYYY. Carrier is the company the block was originally assigned to; numbers may since have been ported to another carrier.

Questions about area code 423

Where is area code 423?
Area code 423 is in Tennessee. It covers Chattanooga, Johnson City, Kingsport, Cleveland, Morristown, Bristol and 22 more cities and towns.
What time zone is area code 423?
Area code 423 spans two time zones: Eastern and Central. Check the caller's city before you call back.
Is 423 a toll-free number?
No. 423 is a geographic area code in Tennessee. Toll-free numbers in the US start with 800, 833, 844, 855, 866, 877 or 888.
Why does 423 share its area with 729?
423 and 729 form an overlay: they cover the same territory, so new numbers there can get any of these codes, and local calls need all 10 digits.
Will area code 423 run out of numbers?
NANPA's latest forecast projects the 423/729 overlay to exhaust in the first quarter of 2081. Before that happens, a new area code is usually added as an overlay; existing numbers keep their code.

Other area codes in Tennessee