Area Code
Michigan, United States
Local Time
12:08 PM
Eastern Time
Area Code
231
State / Province
Michigan
Country
United States
Time Zone
Eastern Time
Area code 231 covers 99 rate centers across Michigan. Rate centers are geographic areas used by telephone companies to determine local calling boundaries.
Use the E.164 format for clickable phone links (RFC 3966):
<a href="tel:+12315550100">+12315550100</a><a href="tel:+12315550199">+12315550199</a>Area code 231 is a North American Numbering Plan (NANP) telephone area code assigned to Michigan, United States. It is one of 12 area codes serving Michigan. As population and demand for phone numbers grew, the region was divided into multiple numbering plan areas to avoid exhausting the available 7-digit number pool.
Yes. 231 is an active North American Numbering Plan (NANP) area code, currently assigned to Michigan, United States. It is safe to answer or dial calls using this area code.
Area code 231 covers 99 rate centers across Michigan. Communities served include Alanson, Alba, Alden, Amble, Baldwin, and 94 more localities. Rate centers are the geographic building blocks telephone carriers use to determine local calling boundaries and to assign numbers when a business or individual requests a phone number in a specific city.
All numbers in the 231 area code observe Eastern Time (IANA timezone: America/New_York). Eastern Time is UTC−5 in winter (EST) and UTC−4 in summer (EDT). When placing a call to a 231 number from a different time zone, check the current local time above to avoid calling outside of business hours.
From within Michigan, dial the 7-digit local number directly if calling within the same rate center, or dial 1 + 231 + 7-digit number for long-distance calls within North America. From outside the US or Canada, dial your country's international exit code followed by 1 231 XXX XXXX. The country code for both the United States and Canada in NANP is +1.
Format 231 numbers using E.164 notation as required by RFC 3966: prefix with +1 and omit dashes and parentheses (e.g., +12315550100). This format ensures tel: links work correctly on all mobile browsers and VoIP apps. See the tel: URI formatting guide for complete examples.