Connecticut has four area codes, each serving different regions of the state. Area code 203, one of the original and oldest area codes established in 1947, covers southwestern Connecticut, including Fairfield County, New Haven County, and parts of Litchfield County. Area code 860, which was split from 203 in August 1995, serves northern and southeastern Connecticut. Area code 959, an overlay of 860, was introduced in August 2014. Since November 2009, all calls originating from area codes 203 or 860 must be dialed with 10 digits, starting with the area code, even for calls within the same area code. The implementation of area code 475 took place on December 12, 2009. Interestingly, the city of Meriden holds a unique position in Connecticut as the only city where residents can make toll-free calls to towns in either the Hartford or New Haven exchanges from a home landline phone.
Connecticut has the lowest rate of adults who rely exclusively on mobile in the nation at 62.0%, yet it has seen the largest gain since 2019—adding nearly 19 percentage points from 43.1%. Data from 2023 shows that Connecticut residents who primarily use a wireless phone make up 21.5%, while 8.3% use both mobile and landline. Those who mainly rely on landlines and those who only use landlines have declined to 4.3% and 2.7% respectively. The proportion of adults without phones stands at 1.3%. Despite retaining the strongest landline culture among states, Connecticut is catching up rapidly to the national wireless trend.