Connecticut is currently using four area codes. Connecticut utilizes two area code overlay plans, often called an overlay complex.
Area code 203 originally covered all of Connecticut when it was established in 1947. It was not until 1995 that Connecticut experienced sufficient growth in population and telephone use to need an additional area code. It was at that time that area code 203 was split to form area code 860. In 2009 area code 475 was put into use as an overlay of area code 203. In 2014 area code 959 was put into service as an overlay of area code 860.
Today area code 203 and 475 covers southwestern Connecticut including Bridgeport, Danbury and New Haven. Area codes 860 and 959 covers eastern and northern Connecticut including Bristol, Hartford and Norwich.
Changes and History of Connecticut Area Codes:
Area code 203 was put into service. In 1995 Area code 203 was split to form area code 860. In 2009 area code 203 was overlaid with area code 475.
Area code 860 was put into service. Area code 860 was created from a split of area code 203.
Area code 475 was put into service. Area code 475 is an overlay of area code 203.
Area code 959 was put into service. Area code 959 is an overlay of area code 860.