423 Area Code: Chattanooga, Tennessee
Area code 423 serves Chattanooga, Johnson City and Bristol, Tennessee in the Eastern and Central time zone, in service since 1995. Consumers have filed 6,494 unwanted-call complaints against 5,775 different 423 numbers, 1,055 of them with the FTC in the last 30 days. Look up the exact number that called you below.
Area code 423 at a glance
- State
- Tennessee
- Main cities
- Chattanooga, Johnson City, Bristol, Cleveland, Kingsport, Morristown + 65 more
- Counties
- Hamilton County, Sullivan County, Washington County, Bradley County + 21 more
- Local time
- —Eastern—Central
- In service since
- September 11, 1995
- Split from
- 615
- Overlay code
- 729 (2025)
- Codes split off
- 865 (1999)
- Local dialing
- 10 digits (area code + number)
- Exchanges
- 75 rate centers, 764 prefixes
Sources: NANPA area code and central office code records (refreshed weekly); cities and counties matched from US Census Bureau and USGS place names.
Most-reported 423 numbers
Ranked by FTC Do Not Call complaints this month, then all-time FTC and FCC complaints. Only numbers with enough complaints for a full report page are listed. Click one for what it was reported for and where.
What calls from 423 numbers are about
3,453 FTC Do Not Call complaints about 423 numbers since Jul 24. The most common named subject is medical & prescriptions, at 20% of complaints (73% of those were recorded messages). Overall, 66% of callers who answered said the call was a robocall.
FTC complaint subjects
- Other / unspecified1,53444%
- Medical & prescriptions68920%
- Impostor (government, business, family)3129%
- Debt reduction3029%
- No subject given2537%
- Dropped call / no message1895%
- Warranties & protection plans742%
FCC complaints by call type, last 2 years
- Prerecorded Voice23459%
- Live Voice13935%
- Text Message246%
Live-voice calls are from a person; prerecorded calls are robocalls.
When 423 spam calls come in
32% of complaints that give a call time describe calls between 10am and 1pm. 96% came Monday to Friday, most on Tuesdays, the pattern of call-center robocall campaigns that run on business hours. Times are as consumers reported them to the FTC.
By hour of the day
By day of the week
Is it getting worse?
1,036 FTC complaints about 423 numbers in the last four weeks, down 10% on the four weeks before. FCC complaints about 423 numbers peaked in 2017 (426); the FTC's daily Do Not Call data has carried most of the volume since mid-2026.
FTC complaints per week
FCC complaints per year
Years shown as '15 to '26; the current year is partial.
Who gets these calls
77% of the FTC complaints about 423 numbers came from people whose own phone number also starts with 423, and 76% from Tennessee. Calls that look local to the person receiving them are the signature of neighbor spoofing: robocallers display a number from your own area code because you're more likely to answer.
Where complainants live
- Tennessee2,62776%
- Georgia2718%
- Florida652%
- California471%
- Texas461%
What people with 423 numbers report
People whose own number starts with 423 filed 4,570 FTC complaints since Jul 24. 58% were about calls showing another 423 number. The most common named subject was debt-relief pitches.
Area codes on the calls they reported
- 423 (same code)2,66758%
- 833 (toll-free)1583%
- 877 (toll-free)1122%
- 866 (toll-free)1112%
- 855 (toll-free)1012%
Likely campaigns using 423 numbers
Groups of numbers that drew the same FTC complaint in the same pattern over the last 60 days. The grouping is statistical and doesn't identify who is calling.
Busiest 423 prefixes this month
FTC complaints in the last 30 days, grouped by the first six digits. When one prefix collects complaints about many different numbers, a campaign is usually cycling through that block. The carrier is who NANPA assigned the prefix to, not who made the calls.
Carriers operating in 423
NANPA has assigned 764 423 prefixes (NPA-NXX central-office codes) across 75 rate centers: 34% to wireless carriers, 65% to landline and VoIP operators; 74% are pooled blocks shared by several carriers. 10 prefixes were assigned in the last 12 months (newest 2026-09-28). The carrier holding a prefix is who the number was issued through. It says nothing about who is calling, since caller ID is routinely spoofed.
| Carrier | Type | Prefixes | Rate centers | Newest assignment |
|---|---|---|---|---|
| BellSouth (AT&T) | Incumbent landline (ILEC) | 119(16%) | 27 | 2011-10-26 |
| CenturyLink (Lumen) | Incumbent landline (ILEC) | 83(11%) | 22 | 2012-02-21 |
| Verizon Wireless (Cellco Partnership) | Wireless | 80(10%) | 22 | 2026-09-02 |
| AT&T Mobility (New Cingular Wireless PCS) | Wireless | 80(10%) | 22 | 2026-09-28 |
| Onvoy (Sinch) | Competitive / VoIP (CLEC) | 54(7%) | 36 | 2023-08-22 |
| Level 3 (Lumen) | Competitive / VoIP (CLEC) | 38(5%) | 23 | 2023-05-18 |
| PAETEC (Windstream) | Competitive / VoIP (CLEC) | 33(4%) | 20 | 2022-06-30 |
| Bandwidth.com | Competitive / VoIP (CLEC) | 30(4%) | 22 | 2026-04-23 |
| T-Mobile USA | Wireless | 25(3%) | 11 | 2023-04-06 |
| Powertel Atlanta Licenses, INC. | Wireless | 21(3%) | 3 | 2025-09-25 |
| Comcast (Xfinity Voice) | Competitive / VoIP (CLEC) | 17(2%) | 15 | 2024-05-14 |
| Powertel Nashville Licenses, INC. | Wireless | 17(2%) | 4 | 2022-11-04 |
Largest rate centers (exchanges) by prefixes: Chattanooga (183), Johnson City (67), Bristol (38), Cleveland (33), Kingsport (32), Morristown (28), Athens (22), Greeneville (20), La Follette (16), Newport (15). Source: NANPA Central Office Code Utilized Assignments (public, refreshed weekly).
What to do about calls from 423 numbers
Before you call back
- Medical & prescriptions is the top named complaint here. Don't confirm your Medicare or insurance number to a caller. Medicare won't cold-call you to sell braces, test kits or plans. Read about Medicare scam calls.
- Look up the full number above. A missed call from 423 with no voicemail is usually a robocall; anyone who needs you will leave a message.
- If it looks like a neighbor's number, it may be spoofed. See calls from your own area code.
- Block repeat callers: iPhone, Android, or your carrier's free filter (Verizon, AT&T, T-Mobile).
Report it in Tennessee
- Unwanted sales calls and robocalls: donotcall.gov (FTC). Scams and fraud: ReportFraud.ftc.gov.
- Spoofing, texts and call-blocking problems: FCC consumer complaints.
- State complaints: Tennessee Attorney General.
- Tennessee is one of the states that maintains its own Do Not Call registry alongside the federal National Do Not Call Registry, so telemarketers calling Tennessee numbers are expected to check both lists. Registering on the federal list at donotcall.gov is free and never expires; the state list is administered separately and may have its own registration process and renewal period.
Your FTC and FCC reports are published (without your name or number) in the datasets this page is built from. How to report unwanted calls.
Area code 423: questions answered from the data
Where is area code 423?
Area code 423 serves Chattanooga, Johnson City and Bristol, Tennessee, covering Hamilton County, Sullivan County and Washington County and 22 more counties. It has been in service since September 11, 1995. It was split from area code 615.
What time zone is area code 423 in?
Area code 423 spans Eastern and Central time. Most of it is in the Eastern zone (UTC−5, or UTC−4 during daylight saving time). The current local time in each zone is shown at the top of this page.
Which area codes overlay 423?
729 (in service 2025) serves the same area as 423. New numbers there can be issued with any of these codes, and local calls need all 10 digits. A spoofed call can display any of them.
What are calls from 423 numbers usually about?
Since Jul 24, consumers filed 3,453 FTC Do Not Call complaints about 423 numbers. The most common named subject was medical & prescriptions: 20% of complaints, 73% of them recorded messages. Across all subjects, 66% of callers who answered the question said the call was a robocall.
When do 423 spam calls happen?
32% of the complaints that give a call time describe calls between 10am and 1pm, and 96% came on weekdays, most often on Tuesday. Times are as consumers reported them.
Are calls from 423 numbers really local?
Not necessarily. 77% of the FTC complaints about 423 numbers came from people whose own phone number also starts with 423, and 76% from Tennessee. Calls that look local to the person receiving them are the signature of neighbor spoofing: robocallers display a number from your own area code because you're more likely to answer.
Are 423 robocalls increasing?
In the four weeks to Oct 20, consumers filed 1,036 FTC complaints about 423 numbers, 10% fewer than the four weeks before.
How do I report a 423 scam call in Tennessee?
Report unwanted sales calls and robocalls to the FTC at donotcall.gov, and scams to ReportFraud.ftc.gov. The FCC takes complaints at consumercomplaints.fcc.gov. In Tennessee, the Tennessee Attorney General also handles consumer complaints about scam calls. Reports feed the public data this page is built from.
Other Tennessee area codes
Sources: FTC Do Not Call complaints (unverified consumer reports), published every weekday and available here from Jul 24; FCC Consumer Complaint Data, public record, imported nightly; NANPA numbering records. A number appearing here means consumers reported calls that displayed it. Caller ID can be spoofed.