North American area code 931 is the telephone area code serving a horseshoe-shaped region of 28 counties in Middle Tennessee. It covers almost all of Middle Tennessee except for the Nashville metropolitan area.
The 931 area code was created in 1997 from area code 615, which had previously covered almost all of Middle Tennessee, but afterwards was restricted to the inner ring of Nashville. Area code 931 began operation on September 15, 1997. Permissive dialing of 615 continued across Middle Tennessee until January 15, 1998.