ZIP codes
160
Area Code 423
Explore ZIP codes in area code 423 — covering TN — 160 ZIP codes — 1,496,833 residents. Population, income, and housing at a glance.
Population
1,496,833
States
TN
Median household income (avg.)
$57,214
Average home value
$193,262
Where is area code 423?
Area code 423 maps to 160 indexable ZIP codes on US5 across TN, with a combined ZIP-area population of about 1,496,833.
Among places with the most population in this NPA on US5 are Chattanooga, TN, Johnson City, TN, Kingsport, TN, Cleveland, TN, and Morristown, TN. Open any ZIP below for full demographics, housing, and nearby services.
The most populous ZIP currently listed for 423 is 37421 (about 52,516 residents).
Income and housing in 423
Across ZIPs with income data in area code 423, the average median household income is about $57,214 — about 24% below the U.S. median ($75,149).
Average median home value across those ZIPs is about $193,262.
On this page’s income ranking, ZIP 37350 is near the top at about $195,063.
How area code 423 numbering works
In the North American Numbering Plan, the first three digits of a 10-digit phone number are the Numbering Plan Area (NPA), commonly called the area code. Digits 4–6 are the central office code (NXX / “exchange”), and the last four digits identify the individual line.
US5’s 423 page groups ZIP codes that are associated with this NPA in published geography data. That is a place-based view — it is not a live directory of every phone number assigned to 423, and overlays or split NPAs can mean multiple area codes serve the same metro.
Scams and caller ID spoofing
Seeing area code 423 on caller ID does not prove the caller is physically in TN. Spoofing tools can display almost any NPA, including local-looking numbers used in IRS, bank, warranty, and “grandparent” scams.
If you receive an unexpected call about taxes, arrests, or locked accounts: hang up, do not share codes or remote-access software, and contact the organization using a number from its official website or your statement — not a number the caller provides. US5 publishes geography for research; it does not verify live callers.
ZIP codes in area code 423
Frequently asked questions
Where is area code 423?
Area code 423 is associated with ZIP codes in TN on US5, covering about 1,496,833 combined ZIP-area residents across 160 codes. Browse the ZIP table on this page for cities and counties.
How many ZIP codes are in area code 423?
US5 currently lists 160 indexable ZIP codes for area code 423. Counts can change as geography publishes update.
What is the average income in area code 423?
The average of ZIP median household incomes in area code 423 is about $57,214 (about 24% below the U.S. median ($75,149)). Individual neighborhoods vary — sort the ZIP table by income to compare.
What is an NXX or “number block” in area code 423?
After the area code, the next three digits (NXX) identify a central office / exchange “block” of up to 10,000 numbers. US5 focuses on ZIP geography for 423; for live number assignment details, use official NANPA / carrier resources.
Does a 423 caller ID mean the person is local?
No. Caller ID can be spoofed to show area code 423 even when the caller is elsewhere. Treat unexpected calls about money, arrests, or account lockouts as suspicious and verify through official channels.
How can I avoid phone scams that use area code 423?
Do not trust caller ID alone. Never send gift cards, wire money, or install remote-access apps because a caller claims to be from the IRS, a bank, or tech support. Hang up and call back using a published number from a statement or official website.
What cities use area code 423?
Larger population clusters on US5 for 423 include Chattanooga, TN, Johnson City, TN, Kingsport, TN, Cleveland, TN, and Morristown, TN. Open linked ZIP pages for neighborhood-level demographics.