By the mid-1990s, Chicago’s continued growth and the proliferation of cell phones and pagers made it apparent that the city needed a new area code. It was decided to split off all of the city outside the downtown area as 773. The new area code went into effect on October 12, 1996.

When did 312 area code start?

Area code 312 was assigned to one of the original 86 numbering plan areas (NPAs) created in 1947 for the North American Numbering Plan.

When was the 708 area code created?

The 708 area code was created in 1989 as the first area code for the Chicago suburbs. Before that, nearly all the six-county Chicago area was included under the 312 area code.

Chicago residents will still be able to get a 312 or 773 number “for the foreseeable future” when signing up for new cell phone service or adding a residential line, Illinois Commerce Commission spokesman Brian Sterling said.