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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

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.

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.

2017 ? - 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 2017.



Projected Future Overlays As of October 2016
847/224 - Early 2029
312/773/872 - Fall 2033
815/779 - more than 30 years
630/331 - more than 30 years

Downstate:
217 - Fall 2019 (an overlay of 447 is planned)
618 - Early 2022 (an overlay of 730 is planned)
309 - Early 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.
Written / Compiled for Telecom Chicago
a part of Telecom Indiana