Reported (331) XXX-XXXX phone numbers lookup

Area Code 331 History and Coverage

Area code 331 was put into use in 2007 as an overlay of the existing 630 numbering plan territory in northeastern Illinois. Unlike introducing a new geographical service area, area code 331 was added to the same region as 630. It increased the number of possible numbers in the numbering plan, but did not alter the existing regional boundaries. This decision was based on high demand for numbers in the well-developed western suburbs of Chicago.

In 1996, the territory of 630 was created by the splitting off of area code 708. In such a way, most of the western suburbs of the city were separated from the 708 service area. By the time 331 area code was implemented, the western suburbs of Chicago were already one of the biggest employment and residential areas of northeastern Illinois.

The common 331 and 630 territories include Cook and Will counties and communities that have a connection to each other with suburban corridors. For instance, Interstate 88 goes through the main westward corridor and Interstate 355 goes through the well-established business and residential districts. The numbering plan covers the inner western suburbs and the area near Fox River.