Area coe 412 is a Commonwealth of Pennsylvania telephone area code which serves most of Allegheny County, Pennsylvania (including Pittsburgh), except the northern edge of Allegheny County served by the North Pittsburgh Telephone Company including Wexford and Gibsonia. Area code 412 was one of the original area codes established in 1947. It is overlaid by and surrounded by area code 878, and is also surrounded by area code 724.