Area code 231 is a telephone

area code A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, rea ...

in the

North American Numbering Plan The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the international callin ...

(NANP) for the northwestern portion of the

Lower Peninsula The Lower Peninsula of Michigan – also known as Lower Michigan – is the larger, southern and less elevated of the two major landmasses that make up the U.S. state of Michigan; the other being the Upper Peninsula, which is separated by the S ...

in the

U.S. state In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...

Michigan Michigan () is a state in the Great Lakes region of the upper Midwestern United States. With a population of nearly 10.12 million and an area of nearly , Michigan is the 10th-largest state by population, the 11th-largest by area, and the ...

History

Area code 231 was created in June 1999 by an

area code split In telecommunications, an area code split is the practice of introducing a new telephone area code by geographically dividing an existing numbering plan area (NPA), and assigning area codes to the resulting divisions, but retaining the existing ar ...

of area code 616, which had served the entire western half of the Lower Peninsula, extending west from the north-south line aligned with the

Mackinac Bridge The Mackinac Bridge ( ) is a suspension bridge spanning the Straits of Mackinac, connecting the Upper and Lower peninsulas of the U.S. state of Michigan. Opened in 1957, the bridge (familiarly known as "Big Mac" and "Mighty Mac") is the worl ...

. 231 was carved out of the northern part. It is centered around the western half of the territory generally defined as

Northern Michigan Northern Michigan, also known as Northern Lower Michigan (known colloquially to residents of more southerly parts of the state and summer residents from cities such as Detroit as " Up North"), is a region of the U.S. state of Michigan. A popul ...

. It also includes Muskegon, which is usually counted as part of

West Michigan West Michigan and Western Michigan are terms for an arbitrary region in the U.S. state of Michigan's Lower Peninsula. Most narrowly it refers to the Grand Rapids- Muskegon-Holland area, and more broadly to most of the region along the Lower Pe ...

Service area

Area code 231 includes (but is not limited to) the following communities: In addition, 231 also includes Bois Blanc Township, which is part of the Upper Peninsula. It is the only municipality in the Upper Peninsula that uses 231, while the rest uses

906 __NOTOC__ Year 906 ( CMVI) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. Events By place Europe * February 27 – Battle of Fritzlar: The Conradines defeat the Babenberg co ...

External links

Planning letter 167, which details 231's creation
(PDF)

at

North American Numbering Plan Administration The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the international calling ...

's website
List of exchanges from AreaCodeDownload.com, 231 Area Code
Telecommunications-related introductions in 1999

231 Year 231 ( CCXXXI) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Claudius and Sallustus (or, less frequently, year 984 '' Ab urbe ...

West Michigan Northern Michigan {{areacode-stub