Spam calls from area code 423? Here's how to stop them.
Area code 423 covers Chattanooga, TN — but the spammers calling from it are faking the number. Here's why, and how to block it free.
If your phone keeps lighting up with area code 423 calls, here's the truth: it's almost certainly not someone in Chattanooga, TN. It's a robocaller spoofing a east Tennessee number so the call looks local and you pick up. You hang up, they dial the next 423 number. You're one row in a spreadsheet.
Don't block 423 — screen it. Real calls come from 423 too. Known callers should ring through; unknown 423 numbers should hit a wall first.
What 423 actually is
Across a sample of 18,440 recent FTC reports (through 2026-07-23), consumers logged 64 complaints about calls that displayed a 423 number. Because caller ID is spoofed, almost none actually originated in Chattanooga — the number is a costume, and this is how often it gets worn against people who share it.
423 is a newer code. Its middle digit (2) was impossible before 1995 — back then the middle digit was locked to 0 or 1. When those ran out, the plan opened up 2–9, and codes like 423 were minted, almost always as overlays stacked on an older code in the same place. Newer overlay codes are prime spoofing material because they still look local but nobody has them memorized.
423 is one of 7 area codes serving Tennessee — the others are 615, 629, 731, 865, 901 and 931 — and 423 specifically covers east Tennessee. That geographic specificity is the whole point of the spoof: a scammer picks the code that looks closest to you.
One tell the spoof can't hide: time. Numbers on 423 belong to the Central time zone. A "local" 423 call that rings at 3 a.m. almost always originated in a boiler room several zones away, dialing your daytime from their own.
Why 423 keeps calling you
Spoofing engines pull the first six digits of your number and dial matching 423 numbers — the “neighbor” trick. A call sharing your area code and prefix feels safe, so answer rates jump. That's the whole scam: familiarity. Read the mechanics in neighbor spoofing, and why you got picked in why me?
Shut down 423 spam calls — free
- Silence unknown callers. The single biggest win. Set it up on iPhone or Android in 30 seconds.
- Turn on your carrier's filter. Free on AT&T, Verizon, and T-Mobile.
- Register on the Do Not Call list. Won't stop scammers, but it makes the legal ones back off and gives you standing to report.
- Weaponize the rest. The calls that still get through? Hand them to the Crew — an AI answers in character and wastes the scammer's time on a call they thought was a real mark.
Why am I getting spam calls from area code 423?
Because auto-dialers spoof it. They fake a 423 (Chattanooga, TN) number so the call looks local and you answer. The caller is almost never actually in Chattanooga — the number is a mask, and a newer overlay like 423 picks it precisely because it looks close to you. See neighbor spoofing.
Is a call from 423 always spam?
No. Real people and businesses in Chattanooga use 423 too, so blanket-blocking it costs you real calls. Screen instead: known contacts ring through, unknown 423 numbers get checked first.
How do I stop 423 spam calls for free?
Turn on Silence Unknown Callers (iPhone / Android), register on the Do Not Call list, and switch on your carrier's free spam filter. For the ones that still slip through, hand them to the Crew — the AI answers in character (in English, Spanish, Russian, or Mandarin) and wastes the scammer's time instead of yours.