Area codes 630 and 331 under the North American Numbering Plan in the United States, cover portions of Chicago's near and far western suburbs, including the majority of DuPage County, Illinois. To the northwest, the area codes also cover a small, neighboring portion of Cook County, including parts of Schaumburg, Streamwood and Hanover Park. To the west, Kane County is divided between area codes 847 and 224 in the north, including Elgin, and area codes 630 and 331 in the south, including Aurora. To the south, the northern part of Will County and a small part of southern Cook County, including the village of Burr Ridge and parts of the village of Lemont, are also included in the 630 and 331 area codes. To the southwest, the city of Yorkville, in exurban Kendall County, is included, as well. The main area code, 630 was split off from area code 708 on August 3, 1996 in a three-way split, with the southern suburbs keeping 708 and the northern suburbs splitting into 847. Within a decade, 630 was close to exhaustion due to the explosive growth of the Chicago suburbs and the proliferation of cell phones and pagers. On October 7, 2007, area code 331 began overlaying area code 630, making ten-digit dialing mandatory in the area. 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. Communities included Addison Aurora Bartlett Batavia Bensenville Big Rock Bloomingdale Bolingbrook Boulder Hill Bristol Burr Ridge Campton Hills Carol Stream Clarendon Hills Darien Downers Grove Elburn Elmhurst Geneva Glendale Heights Glen Ellyn Hanover Park Hinsdale Itasca Kaneville La Fox Lemont Lily Lake Lisle Little Rock Lombard Medinah Millbrook Montgomery Mooseheart Naperville North Aurora Oak Brook Oakbrook Terrace Oswego Plano Plattville Roselle Schaumburg St. Charles Streamwood Sugar Grove Villa Park Virgil Warrenville Wayne Wasco West Chicago Westmont Wheaton Willowbrook Winfield Wood Dale Woodridge Yorkville See also List of North American Numbering Plan area codes List of Illinois area codes References External links Map of Illinois area codes at North American Numbering Plan Administration's website List of exchanges from AreaCodeDownload.com, 630 Area Code List of exchanges from AreaCodeDownload.com, 331 Area Code 630 630 Telecommunications-related introductions in 1996 Telecommunications-related introductions in 2007