Area codes 860 and 959 are telephone area codes in the North American Numbering Plan in the U.S. state of Connecticut. They are arranged in an overlay plan that covers most of the state, except its southwest, which uses area codes 203 and 475.
Area code 860 was created on August 28, 1995, as a numbering plan area split from area code 203, in which the latter was reduced to Fairfield County (except for Sherman) and New Haven County, plus part of Litchfield County (Bethlehem, Woodbury, and a small part of Roxbury). Dialing of area code 860 became mandatory on October 4, 1996.
Area code 959 was originally announced in August 1999 to overlay area code 860, but implementation efforts were delayed for over a decade, culminating in an effective starting date for operation of August 30, 2014. Nevertheless, all calls within Connecticut required ten-digit dialing as of November 14, 2009.
In August 1999, the Connecticut Department of Public Utility Control proposed an area code overlay for numbering plan area 860, adding the new area code 959. This proposal was postponed for nearly a decade due to number conservation measures; in September 2008, the overlay was scheduled within two years (as of August 30, 2011, an activation date for 959 had not been announced). In March 2009, it was announced that the 203/475 overlay would be activated on December 12, 2009, with the 860/959 overlay becoming active by 2011.
Even though the 959 area code did not have a specific start date, all callers in Connecticut were required to dial ten digits, including the area code. A leading 1 is required for originating toll calls from landlines, effective November 14, 2009, to reach another Connecticut number, including calls involving two numbers with the same area code.
On August 27, 2013, the NANPA issued Planning Letter 456 which states that the 959 area code would go into effect on August 30, 2014.[1] The first 959 area code numbers were distributed in December 2015.[2]
| North: 413, 508/774 | ||
| West: 518/838, 845/329 | Area codes 860 and 959 | East: 401 |
| South: 203/475, 631/934 | ||
| Massachusetts area codes: 413, 508/774, 617/857, 781/339, 978/351 | ||
| New York area codes: 212/646/332, 315/680, 516/363, 518/838, 585, 607, 631/934, 716/624, 718/347/929, 845/329, 914, 917 | ||
| Rhode Island area codes: 401 | ||