231 Area Code — MI
Area code 231 serves MI in the Eastern time zone, in service since 1999. The FCC has 98 unwanted-call complaints against 94 different 231 numbers on record. Look up the exact number that called you below.
Most-reported 231 numbers
Ranked by FCC unwanted-call complaints. Click a number for its full report.
231 unwanted-call complaints, last 12 months
Monthly FCC complaint volume against 231 numbers. Spikes usually mark an active robocall campaign cycling through the code.
About area code 231
- Serves
- MI
- Time zone
- Eastern
- In service since
- 1999-06-05
- Overlay
- No
Source: NANPA numbering records, refreshed weekly.
Spam calls from 231? What to know
Seeing repeated missed calls from 231 numbers you don't recognize is the classic signature of neighbor-spoofing robocall campaigns. The caller isn't necessarily in MI — spoofing software displays whatever digits the campaign chooses. Never call unknown numbers back; look them up first, and report unwanted calls to the FCC to build the public record.
Area code 231 FAQs
Where is area code 231?
Area code 231 serves MI, in the Eastern time zone. It has been in service since 1999.
Why do I keep getting calls from 231 numbers?
Robocallers use "neighbor spoofing" — displaying a number with a local area code to make you more likely to answer. A call showing area code 231 may not originate from MI at all. Look up the full 10-digit number on this site to see its complaint history before calling back.
Are 231 numbers safe to call back?
Area codes themselves are neither safe nor unsafe — 231 contains millions of legitimate lines alongside any spoofed or spam numbers. The FCC has logged 98 unwanted-call complaints against 94 distinct 231 numbers in our current data window. Check the specific number's report page before returning a missed call.