231 area code
Muskegon area, Eastern Time.Area code 231 covers Muskegon, Traverse City, Petoskey and 96 more places in Michigan, on Eastern Time.
Right now in Muskegon
Eastern Time (EST, UTC-5; EDT, UTC-4 in summer)
Calling hours: Every day, 9 AM to 9 PM (Michigan law)
Small talk
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Where 231 numbers come from
Numbers are issued by rate center, a billing area named for its main town. 231 has 99. Each one's share is how many 231 numbers start there. Its biggest metro area is Grand Rapids-Wyoming-Kentwood, MI.
- Muskegon12%
- Traverse City9%
- Petoskey4%
- Cadillac4%
- Big Rapids3%
- Ludington2%
- Cheboygan2%
- Manistee2%
Also: Kalkaska, Fremont, Newaygo, Boyne City, Beulah, Charlevoix, Frankfort, Harbor Springs, Hart, Northport, Reed City, Evart + 79 more
Share of exchanges (blocks of 10,000 numbers). Source: NANPA rate center and exchange reports, November 10, 2026
When can you call a 231 number?
Sales calls to homes and cell phones have legal hours, set by Michigan law. Hold every 231 number to them, since you can't tell a work line from a personal cell.
What applies to 231Every day, 9 AM to 9 PM
- Federal (TCPA and FTC rule)Every day, 8 AM to 9 PMCalls to residential and mobile numbers. Most calls to businesses are exempt from the FTC's rule.47 CFR 64.1200(c)(1); 16 CFR 310.4(c) (opens in a new tab)
- Michigan lawEvery day, 9 AM to 9 PMIn a harassment statute that needs intent to annoy.MCL 750.540e(1)(f) (opens in a new tab)
Local time comes from the area code, not from where the person is today. Mobiles keep their number when they move. Calling hours here are a guide, not legal advice. Every state's calling hours, with sources
The 231 area code
231 went into service on June 5, 1999, split off from 616. Local calls can still be dialed with 7 digits.
- 1999231 starts
Source: NANPA area code database
Calling a list of 231 numbers?
Paste it into the free phone number validator. It checks every number, finds each one's time zone and sorts the list by who you can call right now.
231 area code FAQ
What area code is 231?
231 is a Michigan area code for Muskegon, Traverse City, Petoskey, Cadillac and 95 more places.
What time zone is the 231 area code in?
Eastern Time (EST, UTC-5; EDT, UTC-4 in summer).
What are the calling hours for 231 numbers?
Every day, 9 AM to 9 PM, local time, under Michigan law.
When did the 231 area code start?
On June 5, 1999. It was split from 616.
Calling 231 numbers? Reach more of them.
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