231 area code
Where the 231 area code is, its overlay and how to dial a +1 231 number from anywhere.
The 231 area code is in Muskegon, Michigan, United States (Eastern (ET)). To call from abroad: +1 231 555-0123.
The 231 area code is a geographic North American Numbering Plan (NANP) code covering Muskegon, Michigan. It has been in service since 11-Mar-1999 and sits in the Eastern (ET) time zone.
How to dial a 231 number
+1 231 555-01231 231 555-0123Cities in the 231 area code
A 231 number is usually in one of these places in Michigan — 2 counties.
Other Michigan area codes
Frequently asked questions
Where is the 231 area code?
The 231 area code is in Muskegon, Michigan, United States (Eastern (ET)).
Do I have to dial 10 digits for 231?
Local calls within 231 may use seven digits; ten-digit dialling always works.
How do I call a 231 number from another country?
Dial your exit code (or +), then 1, then 231, then the number: +1 231 555-0123.
Source: NANPA numbering plan. An area code covers a region, not a precise address — a 231 number does not pinpoint a street or ZIP code.
Number holders in area code 231
Each prefix (the three digits after the area code) is assigned by NANPA to one telephone company. 596 prefixes are in use in 231, shared by 45 companies. The largest holders:
| Company | Prefixes | Share |
|---|---|---|
| New Cingular Wireless PCS, LLC | 72 | 12% |
| Michigan Bell Tel Co | 72 | 12% |
| Frontier North, Inc. | 52 | 9% |
| Onvoy, Llcv | 49 | 8% |
| Telnet Worldwide, Inc. | 43 | 7% |
| Cellco Partnership Dba Verizon Wireless | 42 | 7% |
Source: NANPA central office code assignments. A number keeps its original prefix when it is ported to another carrier.
Complaints about 231 numbers
- Reports to the FTC, last 30 days
- 785
- Recorded messages or robocalls
- 76%
- Rank among area codes
- #80 of 670
- Most reported subjects
- Other (316)
- Reducing your debt (credit cards, mortgage, student loans) (286)
- Calls pretending to be government, businesses, or family and friends (45)
Period Aug 26 – Sep 24, 2026. These are the numbers shown on the caller ID of the reported calls; many are spoofed and do not belong to the real caller.
Source: US Federal Trade Commission, Do Not Call reported calls data (daily files).
All US area codes United States +1 Map of area code 231 — cities & rate centres