423 area code
Chattanooga area, Eastern and Central Time.Area code 423 covers Chattanooga, Johnson City, Bristol and 72 more places in Tennessee, on Eastern and Central Time. 729 covers the same area.
Right now in Tennessee
Eastern Time (EST, UTC-5; EDT, UTC-4 in summer) · Central Time (CST, UTC-6; CDT, UTC-5 in summer)
Calling hours: Every day, 8 AM to 9 PM (the federal rule)
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Where 423 numbers come from
Numbers are issued by rate center, a billing area named for its main town. 423 has 75. Each one's share is how many 423 numbers start there. Its biggest metro area is Chattanooga, TN-GA.
- Chattanooga24%
- Johnson City9%
- Bristol5%
- Cleveland4%
- Kingsport4%
- Morristown4%
- Athens3%
- Greeneville3%
- La Follette2%
Also: Newport, Elizabethton, Midway (Sullivan), Rogersville, Blountville, Benton, Bulls Gap, Charleston, Sweetwater, Dayton, Erwin, Madisonville + 54 more
Share of exchanges (blocks of 10,000 numbers). Source: NANPA rate center and exchange reports, November 10, 2026
When can you call a 423 number?
Sales calls to homes and cell phones have legal hours, set by the federal rule. Hold every 423 number to them, since you can't tell a work line from a personal cell.
What applies to 423Every day, 8 AM to 9 PM
- Federal (TCPA and FTC rule)Every day, 8 AM to 9 PMCalls to residential and mobile numbers. Most calls to businesses are exempt from the FTC's rule.47 CFR 64.1200(c)(1); 16 CFR 310.4(c) (opens in a new tab)
Local time comes from the area code, not from where the person is today. Mobiles keep their number when they move. Calling hours here are a guide, not legal advice. Every state's calling hours, with sources
423 and 729
423 went into service on September 11, 1995, split off from 615, and 865 was later split off from it. 423 and 729 cover the same area, so new numbers can get either code and neighbors can have different area codes. 423 holds 100% of the area's exchanges; 729 holds the rest. Local calls take all 10 digits.
- 1995423 starts
- 1999865 split off
- 2025729 overlay
Source: NANPA area code database
Calling a list of 423 numbers?
Paste it into the free phone number validator. It checks every number, finds each one's time zone and sorts the list by who you can call right now.
423 area code FAQ
What area code is 423?
423 is a Tennessee area code for Chattanooga, Johnson City, Bristol, Cleveland and 71 more places.
What time zone is the 423 area code in?
It spans two: Eastern Time (EST, UTC-5; EDT, UTC-4 in summer) and Central Time (CST, UTC-6; CDT, UTC-5 in summer). A 423 number can be on either clock.
Is 729 the same as 423?
Same area, different code. 423 and 729 cover the same area (an overlay), so new numbers can get any of them and local calls take all 10 digits.
What are the calling hours for 423 numbers?
Every day, 8 AM to 9 PM, local time, under the federal rule.
When did the 423 area code start?
On September 11, 1995. It was split from 615.
Calling 423 numbers? Reach more of them.
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