NPA - 231 (Michigan)
The 231 area code is part of geographic numbering plan area that includes Michigan.
There are a few special area codes with the last two digits 422 match, these are known as easily recognizable codes (ERCs). The 8xx set of numbers are reserved for toll-free services and communication.
Michigan is a state in the Great Lakes and Midwestern regions of the United States.
Midwestern life feels anything but small there, where stunning lakeshores, deep forests and dramatic cliffs and dunes reveal themselves at every turn. The landscape is matched only by dozens of eclectic towns and one iconic city with a reputation for making great cars and even greater music.
Detroit - "Motor City"
Detroit, teeming with authentic neighborhoods and rich with diverse cuisines, eclectic shopping and stand-out museums. View Diego Rivera’s Detroit Industry Murals at Detroit Institute of the Arts, take a walking tour of Corktown, the city’s oldest ethnic area, or check out the iconic architecture of the Fisher Building.
In the central portions of Detroit, the population of young professionals, artists, and other transplants is growing and retail is expanding.