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. |  | ||
January 2022 - 464 overlays 708 South Chicago Suburbs First 464 code could be ordered October 23th, 2021 Mandatory 1+10 dialing began October 24th, 2021 (for 988) Earliest 464 code activation date January 21st, 2022 Projected Future Overlays As of October 2022 2030 - 847/224 2034 - 815/779 2040 - 312/773/872 2053 - 630/331 2056 - 708/464 Downstate: Spring 2024 - 730 overlays 618 Late 2024 - 861 overlays 309 2035 - 217/447 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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