Area Code Atlas

Overlay 475 proposed for NPA 203

The Connecticut Department of Public Utility Control proposed an overlay plan for area code 203.

Overlay of 475 on 203 ordered

On September 22, 1999, the Connecticut Department of Public Utility Control ordered the overlay of area code 475 on the existing 203 area. This decision was made to address the projected exhaustion of available numbers in the 203 region.

NPA 475 overlay on 203 announced

NPA 475 To Overlay NPA 203; NPA 959 To Overlay NPA 860 (Connecticut)

Update on the Introduction of NPAs 475 and 959 (Connecticut)

NPA 475 overlay on 203 announced

NPA 475 to Overlay NPA 203; NPA 860 10-digit dialing (Connecticut)

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 475 overlaid on 203

Area code 475 was activated as an overlay on the 203 region on December 12, 2009. The overlay provided additional numbering resources for southwestern Connecticut without requiring existing numbers to change. This overlay was first proposed by the Connecticut Department of Public Utility Control in August 1999.