Area Code 423

About Area Code 423

Area code 423 is a geographic telephone area code assigned to Chattanooga, Tennessee. It operates in the Eastern time zone and was first introduced in 1995. Split from 615. East Tennessee.

Within Tennessee, area code 423 shares numbering capacity with 6 other area codes. The state's 7,126,744-person population (2023 Census Bureau estimate) is served by a combined 7 active codes, with 423 primarily responsible for the Chattanooga region. Tennessee's state capital is Nashville, and its largest city is Nashville.

When you receive a call from a 423 number on your Caller ID, the call originated from a phone number assigned to the 423 area code — but be aware that Local Number Portability (in effect since 2003) means the caller could be physically located anywhere in the US or Canada. Area code 423 only confirms where the number was originally assigned.

Where is the 423 area code located?

Area code 423 is assigned to Chattanooga, Tennessee, in the Eastern time zone. The state of Tennessee uses 7 active area codes, and 423 is one of them. Calls placed from the 423 area code originate from numbers assigned by NANPA — the North American Numbering Plan Administrator — and the 423 prefix appears on Caller ID for both landline and wireless calls placed from this region.

The Eastern time zone observes Daylight Saving Time, shifting from UTC-5 to UTC-4 in summer. The local time shown above is always current, so you can quickly check whether it's a reasonable hour to call back.

What cities and counties use the 423 area code?

The 423 area code serves 9 notable cities, listed below in order of population. The largest city in the 423 territory is Chattanooga (181,099 residents in Hamilton County).

• Chattanooga, TN — 181,099 residents (8.1% of 423 numbers)
• Nashville, TN — 689,447 residents (30.8% of 423 numbers)
• Memphis, TN — 621,056 residents (27.7% of 423 numbers)
• Knoxville, TN — 192,648 residents (8.6% of 423 numbers)
• Clarksville, TN — 176,108 residents (7.9% of 423 numbers)
• Murfreesboro, TN — 157,084 residents (7% of 423 numbers)
• Franklin, TN — 83,454 residents (3.7% of 423 numbers)
• Jackson, TN — 67,191 residents (3% of 423 numbers)
• Johnson City, TN — 71,046 residents (3.2% of 423 numbers)

Phone number format in area code 423

All phone numbers within area code 423 follow the standard North American 10-digit format:(423) NXX-XXXX. The NXX is the central office prefix (also called an "exchange") and XXXX is the subscriber line number. For long-distance calls within the NANP, dial 1 + 423 + NXX + XXXX. From outside North America, dial your country's international access code, then 1 (the NANP country code), then the 10-digit number.

If you need to verify whether a specific 423 number is wireless, landline, or VoIP, you can use our reverse phone lookup tool. Be aware that number portability means the area code no longer guarantees the caller's physical location — only where the number was first assigned.

History of area code 423

Split from 615. East Tennessee.

The original 86 area codes were assigned by AT&T and Bell Labs in 1947 as part of the North American Numbering Plan. At the time, rotary-dial phones meant codes with lower digits (like 212 for NYC, 213 for LA, 312 for Chicago) were given to the largest cities because they took less time to dial. Today's area code assignments still reflect those early choices, even though touch-tone and cell phones made the original reason obsolete.

Is the 423 area code safe to answer?

Area code 423 itself is a normal geographic code with no elevated spam risk. That said, scammers can spoof any area code — including 423 — so if you don't recognize the full number, let it go to voicemail and verify the caller's identity before calling back.