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Illinois is currently using thirteen area codes. Illinois currently has three area codes, 447,464, and 730, which
are assigned to provide numbering relief but are not yet in service. Illinois utilizes five area code overlay plans, often called an overlay complex.
Illinois originally had four area codes,
217,312,618 and 815, when the numbering system was established in 1947. It was not until ten years later in 1957 that Illinois experienced sufficient growth in population and telephone use to need an
additional area code. In 1957 area code 309 was created by a split of area codes 217 and 815. These five area codes were sufficient until 1989.
Changes and History of Illinois Area Codes:
01/01/1947
Area code 217 was put into service. In 1957 area code 217 was split, along with a portion of area code 815, to form part of area code 309.
01/01/1947
Area code 312 was put into
service. In 1989 Area code 312 was split to form area code 708. In 1996 area code 312 was split again to form area code 773. In 2009 area code 312 was overlaid with area code 872. |
