Indiana | Illinois | Michigan Illinois - Chicago Chicago Illinois - Area Code History | |||
November 1989 - 708 splits from 312 City of Chicago keeps 312 Effective November 11, 1989 (calls to either 312 or 708 accepted) Permissive ended February 9, 1990 Note: The small 312 area that appears separated from the city is Chicago's O'Hare Airport. The airport is within the city limits of Chicago, connected by a thin section of land. Northern Illinois 815, 708 and 312 
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January 1996 - 847 splits from 708 Chicago North Suburbs Effective January 20, 1996 (calls to either 708 or 847 accepted) Permissive ended April 20, 1996 Dialing: Within HNPA dial 7D, outside HNPA dial 1+10 (HNPA = home NPA of phone used to place call) Note: The original plan to relieve 708 was to overlay 630 across the entire area and move all cellular and pager services into 630. 708 would have become a landline only area code ... landline and wireless would have been allowed in 630. The overlay was converted into a three way split in response to an FCC ban on service specific area codes. |  | ||
August 1996 - 630 splits from 708 Chicago West Suburbs Effective August 3, 1996 (calls to either 708 or 630 accepted) Permissive ended November 30, 1996 Dialing: Within HNPA dial 7D, outside HNPA dial 1+10 (HNPA = home NPA of phone used to place call) This completed the three way split of 708. |  | ||
October 1996 - 773 splits from 312 Chicago Loop keeps 312 Effective October 12, 1996 (calls to either 312 or 773 accepted) Permissive ended January 11, 1997 Dialing: Within HNPA dial 7D, outside HNPA dial 1+10 (HNPA = home NPA of phone used to place call) This was a controversal spilt where everyone in the City of Chicago changed their area code except "Chicago Zone 01" - an area that covers the loop. This allowed major corporations based in downtown Chicago to keep their 312 area code numbers. This was and will be the last split in Illinois. |  | ||
May 1998 - 224 overlays 847 Chicago North Suburbs Permissive 1+10 dialing began May 11, 1998 Expected operational date for 224 was November 7, 1998 As overlays are introduced 1+10 digit dialing becomes mandatory Local and long distance calls are dialed 1+10 digits regardless of the cost of calls (no toll alerting) Operator assisted calls are dialed 0+10 digits |  | ||
August 2006 - 779 overlays 815 Northern Illinois 779 overlays 815 Northern Illinois Earliest 779 code ordering September 17, 2006 Permissive 1+10 dialing began August 19, 2006 Mandatory 1+10 dialing began February 17, 2007 Earliest 779 code activation March 17, 2007 815/779 covers a large area of northern Illinois outside of the Chicago metro area. 
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July 2007 - 331 overlays 630 Chicago West Suburbs First 630 code assigned July 6, 2007 Permissive 1+10 dialing began July 6, 2007 Mandatory 1+10 dialing began October 7, 2007 Earliest 331 code activation October 7, 2007 |  | ||
August 2009 - 872 overlays 312 and 773 City of Chicago Last 773 code assigned July 9th, 2009 First 872 code assigned August 7th, 2009 Permissive 1+10 dialing began August 7th, 2009 (7 digit dialing temporarily remains allowed) Mandatory 1+10 dialing began November 7th, 2009 Area Code 872 numbers can be anywhere in 312 or 773 areas. At this point all areas of northern Illinois and Chicago require 1+10 dialing except the 708 area code. |  | ||
2016 ? - 464 overlays 708 South Chicago Suburbs The 464 area code has been set aside to provide relief for 708 when all exchanges are used. As of October 2014, area code 464 is expected to be needed in late 2016. Projected Future Overlays As of October 2014 847/224 - Summer 2027 312/773/872 - Summer 2036 815/779 - Spring 2037 630/331 - Summer 2043 Downstate: 217 - Early 2018 (an overlay of 447 is planned) 618 - Summer 2020 (an overlay of 730 is planned) 309 - Spring 2029 (area code 309 was introduced in 1957) All areas of Illinois use 1+10 dialing to reach other NPAs Overlaid areas of Illinois require 1+10 dialing for all calls Non-overlaid areas allow 7D dialing for local calls |  | ||
Exchange boundries on this page are based on information from 1994 and may have changed.
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