Area codes 630 and 331

Area codes 630 and 331 are telephone area codes in the North American Numbering Plan (NANP) for portions of Chicago's near and far western suburbs, including the majority of DuPage County, Illinois.

To the northwest, the numbering plan area (NPA) also includes a small portion of Cook County, including parts of Schaumburg, Streamwood and Hanover Park.

To the southwest, the city of Yorkville, in exurban Kendall County, is included, as well.

Within a decade, 630 was close to exhaustion due to the growth of the Chicago suburbs and the proliferation of cell phones and pagers.

The Illinois side of the Chicago area–312/773/872, 708, 847/224, 630/331 and portions of 815/779–is one of the largest local calling areas in the United States; with few exceptions, no long-distance charges are applied from one portion of the metro area to another.