MADISON, Wis. (AP) — A new telephone area code for southern Wisconsin is set to go into effect next month.

The 353 area code will overlay the 608 area code region beginning Sept. 15, the Wisconsin State Journal reported Thursday. Customers requesting new or additional lines in the region will get the new area code. People with an existing 608 area code will keep that number.

The 608 area code is expected to run out of assignable prefixes — the three numbers that follow the area code — by the first quarter of 2024, according to the state Public Service Commission, which regulates utilities in Wisconsin.

The 608 area code includes Madison, Beloit, Janseville, Monroe, La Crosse, Platteville, Wisconsin Dells and at least part of 21 counties, according to the commission.