Find any 312- phone number in Illinois

The 312 area code is an area code within the North American Numbering Plan (NANP). It is a three-digit code covering Chicago and its surrounding suburbs in the state of Illinois. It was first established in 1996 and serves the majority of the Chicago Metropolitan area.

The NANP system is used to break down large geographical territory into smaller, more manageable chunks, and make the space more dial-able. This system was created in 1947 by AT&T and Bell. The NANP designates area codes by the state, and then each area code is broken down into smaller geographic areas, with each geographic area assigned a separate three-digit area code. With more than 70 North American countries using the NANP, the system is versatile, efficient, and provides avenues for scalability.