203 Area Code — New Haven, CT

What is area code 203 and where does it cover?

Area code 203 serves southwestern Connecticut, covering much of Fairfield County, all of New Haven County, and a small part of Litchfield County - including Bridgeport, New Haven, Stamford, Waterbury, Norwalk, Danbury, Greenwich, and Westport. It is overlaid by 475, so new numbers in the same footprint may be assigned 475. Ten-digit dialing is required.

How did area code 203 evolve over time?

• 1947: Connecticut received original code 203 statewide under the first NANP.

• 1995: State split; 860 created for the rest of Connecticut, leaving 203 in the southwest.

• 2009: Overlay 475 added to 203; permissive dialing preceded statewide 10-digit dialing.

These changes responded to number demand from population growth and mobile devices.

What are the current dialing rules for 203/475?

Since late 2009, 10-digit dialing is mandatory for local calls across Connecticut, including the 203/475 region. This change prepared for the 475 overlay (and later 959 over 860). Existing 203 numbers did not change.

Which cities and communities are most associated with 203?

Major communities include Bridgeport, New Haven, Stamford, Norwalk, Waterbury, Danbury, Greenwich, Fairfield, West Haven, Milford, Hamden, and Shelton—core parts of the Connecticut segment of the New York metro area.

What interesting facts are tied to 203?

• One of the original NANP area codes (1947): 203 is among the early U.S. codes assigned when nationwide direct dialing launched.

• Statewide 10-digit dialing came with 203’s overlay era: Connecticut moved the entire state to 10-digit dialing in November 2009, a notable early statewide switch.