Area Code Atlas

Area code 860 split from 203

In 1995, area code 860 was introduced for the majority of Connecticut, reducing the area served by 203 to the southwestern part of the state. The split was implemented to provide additional numbering resources as demand increased.

NPA 860 split from 203

Area code 860 was created on August 28, 1995, when Connecticut was divided into two numbering plan areas. The new code covered the majority of the state outside the southwestern region, while 203 was reduced to serve the southwestern portion including Fairfield County (except Sherman), New Haven County, and part of Litchfield County.

Mandatory dialing for area code 860

Mandatory dialing of area code 860 began on October 4, 1996, following a permissive dialing period after the 1995 split. Callers were required to use the new area code for calls within its region.

Extraordinary NPA-Specific Jeopardy Conservation Procedures Announced for Connecticut NPAs 203 & 860

Overlay of 959 announced for 860

Area code 959 was announced in August 1999 as an overlay for the 860 region due to continued growth in demand for telephone numbers. Implementation was delayed for over a decade because of number allocation changes.

Permissive 10-digit dialing begins for 203, 475, and 860

On May 16, 2009, permissive 10-digit dialing began for area codes 203, 475, and 860 in Connecticut. Callers could use either 7 or 10 digits to complete local calls during this transition period, including specific implementation in the 860 area code.

Mandatory ten-digit dialing implemented for all Connecticut area codes

On November 14, 2009, mandatory ten-digit dialing was implemented statewide in Connecticut in preparation for the 475 overlay on 203 and the planned 959 overlay on 860. This change was part of the broader transition involving area codes 203, 475, 860, and 959, supporting the introduction of new overlay codes, including 959 for the 860 region.

NPA 959 overlay on 860 announced

NPA 959 to Overlay NPA 860 (Connecticut)

NANPA issues Planning Letter 456 for 959 overlay

NANPA issued Planning Letter 456 on August 27, 2013, announcing the in-service date for area code 959 as August 30, 2014, to overlay the 860 region.

NPA 959 overlays 860

Area code 959 was implemented as an overlay for 860 in 2014, providing additional numbering resources for most of Connecticut outside the southwestern region.

Activation of 959 overlay on 860

On August 30, 2014, area code 959 was activated as an overlay on the 860 region of Connecticut, providing additional numbering resources for most of Connecticut outside the southwest. The new code was introduced to address the exhaustion of available numbers in the 860 area, with both codes serving the same geographic region. New telephone numbers in the region could be assigned either the 860 or 959 area code.