The 231 area code covers Muskegon, Traverse City and 86 more places in Michigan.
Area code 231 is in Michigan, on Eastern Time. In the 231 area, phone numbers are given out most in Muskegon County, then Grand Traverse and Emmet counties. It has been in service since June 5, 1999.
- Where
- 8 counties in Michigan, mostly Muskegon County, Grand Traverse County and Emmet County
- Time zone
- Eastern Time
- In service since
- June 5, 1999
- Shares its area with
- No other area code
- Prefixes in use
- 572
- How to dial
- Local calls inside 231 can still be dialed with just 7 digits.
Find out who called you from a 231 number.
Enter the full 10-digit number to see who it is listed to and the city and state on the listing. It is the same free check as our who called me lookup. To see only the caller ID name on the number, use our free CNAM lookup. To see whether it is a mobile, a landline or a VoIP line, use our free VoIP checker. To see which carrier a (231) number is on today, use our free carrier lookup.
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Muskegon holds 12% of the phone prefixes in area code 231.
A prefix is the three digits after the area code, and NANPA assigns each one to a town. Counting the 572 prefixes in use shows where 231 numbers are actually given out.
- Muskegon68 prefixes, 12%
- Traverse City53 prefixes, 9%
- Petoskey22 prefixes, 4%
- Cadillac21 prefixes, 4%
- Big Rapids19 prefixes, 3%
- Ludington14 prefixes, 2%
- Cheboygan13 prefixes, 2%
- Manistee12 prefixes, 2%
Also served: Kalkaska, Fremont, Newaygo and Boyne City and 76 smaller places.
AT&T Mobility and Michigan Bell (AT&T) hold the most phone number prefixes in area code 231, 72 prefixes each.
NANPA, which runs the North American numbering plan, assigns each prefix (the three digits after the area code) to one carrier. Here is how the 572 prefixes in use in 231 divide between carriers; holders this page does not name are grouped as other carriers.
| Carrier | Prefixes | Share |
|---|---|---|
| AT&T MobilityMobile network | 72 | 13% |
| Michigan Bell (AT&T)AT&T's landline company | 72 | 13% |
| FrontierLandline company | 52 | 9% |
| Telnet Worldwide | 43 | 8% |
| 123.Net | 34 | 6% |
| T-MobileMobile network | 28 | 5% |
| 31 other carriers | 271 | 47% |
67% of these prefixes are pooled, which means the blocks of 1,000 numbers inside them can belong to other carriers. Any number can also have been moved to another carrier since, so this shows who holds the prefixes, not who serves a given number.
Want the carrier of one exact number? Our free carrier lookup checks it, because numbers move between carriers.
Source: NANPA central office code assignments, October 1, 2026.
231 has covered the same ground since 1999.
1999
231 starts on June 5, 1999, split off from 616.
A 231 number on your screen can still be a scam, because caller ID is easy to fake.
- Let an unknown call go to voicemail. A real caller leaves a message; a robocaller usually does not.
- Look the number up with the box above before you call back, because calling back tells a robocaller your line is live.
- Hang up on anyone who wants gift cards, crypto or a wire transfer, or asks you to read out a code that was just texted to you.
- Report unwanted robocalls at reportfraud.ftc.gov, or paste a suspicious message into our free scam checker.
The area codes closest to 231 are 989, 616 and 920.
This list measures the distance between the centres of each area, across state lines, and shows codes that share one area together.
These are the questions people ask most about area code 231.
Where is area code 231?
231 covers Muskegon, Traverse City, Petoskey and Cadillac and 84 more places in Michigan. In the 231 area, phone numbers are given out most in Muskegon County, then Grand Traverse and Emmet counties.
What state is area code 231 in?
Michigan. 231 is a Michigan area code on Eastern Time.
What cities use area code 231?
The places holding the most 231 prefixes are Muskegon, Traverse City, Petoskey, Cadillac, Big Rapids, Ludington, Cheboygan and Manistee, out of 88 places in all. The count comes from NANPA's prefix assignments as of October 1, 2026.
Which phone company owns area code 231?
No single phone company owns 231. NANPA's records show the largest holders of its 572 prefixes include AT&T Mobility, Michigan Bell (AT&T) and Frontier. Numbers move between carriers, so check one exact number with a carrier lookup.
What time zone is area code 231 in?
231 is on Eastern Time.
When did area code 231 start?
231 went into service on June 5, 1999, when it was split off from 616.
How do I dial a 231 number?
Local calls inside 231 can still be dialed with just 7 digits.
Is 231 a toll-free number?
No. 231 is a regular area code for Muskegon and Traverse City in Michigan, not a toll-free one. The toll-free codes in North America are 800, 833, 844, 855, 866, 877 and 888.
What area codes are near 231?
The closest are 989 (Saginaw, Michigan), 616 (Grand Rapids, Michigan), 920/274 (Green Bay, Wisconsin) and 810 (Flint, Michigan), measured between the centres of each area.
Who called me from a 231 number?
Enter the full 10-digit number in the lookup above. It returns the listed owner where there is a public record, where the number is registered, and whether it is a mobile, a landline or a VoIP line.
Is area code 231 a scam?
231 is a real Michigan area code, so the code itself is not a warning sign. Scam callers fake local-looking numbers on purpose, so judge the call by what the caller asks for, and look the number up before calling back.
Put this lookup on your site: our free area code widget takes two lines of code and shows any US area code's state, time zone and local time.
Source: NANPA, the North American Numbering Plan Administrator: its area code database and prefix assignments, as of October 1, 2026.