Area Code 203
Connecticut
Area code 203 serves Connecticut, primarily Bridgeport, in the Eastern Time (ET) time zone. It has served the region since 01-Jan-1947.
Overlay Area Code
This area code is part of an overlay region, meaning the same geographic area is served by multiple area codes. Overlay codes were introduced to meet growing demand for phone numbers without requiring existing customers to change their numbers.
This area code shares its geographic region with: area code 475 (Bridgeport).
In service since: 01-Jan-1947
Area Code Splits
Parts of this area code’s original geographic region were later assigned new area codes through splits. When a split occurs, some customers in the original area code region are assigned the new area code.
Split into: area code 860 (Hartford).
Demographics & Economics
- Total Population
- 1,847,298
- Population Density
- 2,063 people/sq miabove U.S. average (U.S.: 93 people/sq mi)
- Median Household Income
- $87,135above U.S. median (U.S.: $75,144)
- Poverty Rate
- 12.8%above U.S. average (U.S.: 11.5%)
- Unemployment Rate
- 4.0%above U.S. average (U.S.: 3.6%)
- Education Attainment
- Bachelor's Degree+23.6%below U.S. average (U.S.: 33.7%)High School or Lower0.0%
Statistics are population-weighted aggregations from Census ACS 5-year estimates. Population figures are approximate — see Sources & Methodology for details on how area code populations are derived.
See how this area code compares to all US area codes in the Statistics dashboard.
Time Zone
- Eastern Time (ET)
NANPA Relief Status
According to the latest NANPA analysis (July 2026), this area code is not currently listed as exhausting within the next 36 months. No relief planning is in progress for this NPA.
Source: NANPA NPA Relief Planning Reports · See all relief planning statuses
Current Time
Prefix Utilization
Geographic Coverage
State
CT
Major Cities
- Bridgeport
- Stamford
- New Haven
- Waterbury
- Norwalk
- Danbury
- Meriden
- West Haven
- Milford
- Shelton
- Naugatuck
- East Haven
- North Haven
- Ansonia
- Wallingford Center
- Greenwich
- Orange
- Derby
- Bethel
- Trumbull Center
- Sandy Hook
- Riverside
- Cos Cob
- Ridgefield
and 79 more cities
Historical Timeline of Area Code 203
Area code 203 is one of the original 86 North American Numbering Plan codes established in 1947, originally covering the entire state of Connecticut. It maintained full-state coverage for 48 years before the 1995 split created area code 860, and received its overlay area code 475 in 2009, completing Connecticut's two-overlay-complex system. Source: Wikipedia — Area codes 203 and 475
- 1947: Area code 203 is created as one of the 86 original NANP codes, covering the entire state of Connecticut as its sole area code. Connecticut was one of the few states served by a single area code from the plan's inception. Source: Wikipedia
- August 28, 1995: Area code 860 splits from 203. The 203 code retains Fairfield County (except Sherman), New Haven County, and select Litchfield County towns (Bethlehem, Woodbury, part of Roxbury). The remainder of the state is assigned 860. Source: Wikipedia Source: CT OCC Brief
- October 4, 1996: Mandatory use of area code 860 begins, completing the first geographic split of Connecticut's numbering plan. Source: CT OCC Brief
- September 22, 1999: Connecticut DPUC formally orders the 475 overlay on the 203 NPA in Docket 96-11-10, initially projected for implementation by 2006. Source: NANPA — Connecticut Area Codes
- April 14, 2009: NANPA issues Planning Letter PL-388 announcing the 475 overlay implementation timeline: permissive 10-digit dialing begins May 16, mandatory 10-digit dialing on November 14, and 475 activation on December 12, 2009. Source: NANPA — Connecticut Area Codes
- December 12, 2009: Area code 475 is placed in service as an overlay on the 203 NPA, covering the same geographic area. The first prefix assigned is (475) 882-4xxx in the Huntington section of Shelton, Connecticut. Source: Wikipedia Source: CT OCC Brief
- 2014: Area code 959 overlay is placed in service on area code 860, completing Connecticut's two-overlay-complex system with 203/475 in the southwest and 860/959 in the rest of the state. Source: Wikipedia
Regulatory History
Area code 203 has undergone six significant regulatory events over 79 years. The Connecticut Public Utilities Regulatory Authority (PURA, formerly DPUC) exercises delegated authority under 47 CFR § 52.19 to manage numbering relief within the state. Source: Connecticut PURA
| Year | Event | Docket | Regulatory Action & Impact |
|---|---|---|---|
| 1947 | NANP established | AT&T Nationwide Numbering Plan | AT&T establishes the North American Numbering Plan. Connecticut is assigned area code 203 as its sole NPA, covering the entire state. The state regulatory authority gains jurisdiction over numbering relief matters. Source: Wikipedia |
| 1995 | 860 split implemented | DPUC Docket | Connecticut DPUC authorizes the creation of area code 860 as a geographic split from 203. The split divides the state into two numbering plan areas: 203 for southwestern Connecticut and 860 for the remainder. Source: CT OCC Brief |
| 1999 | 475 overlay ordered | Docket 96-11-10 | Connecticut DPUC orders NANPA to implement area code 475 as an overlay on the 203 NPA, with initial projected implementation by 2006. The order triggers a decade-long regulatory process involving number conservation measures. Source: PURA Final Decision Database |
| 2009 | 475 overlay implemented | NANPA PL-388 | After a 10-year delay, NANPA places area code 475 in service on December 12, 2009. Permissive 10-digit dialing began May 16, 2009; mandatory 10-digit dialing on November 14, 2009. The overlay covers the same geographic territory as 203. Source: NANPA — Connecticut Area Codes |
| 2009 | Statewide 10-digit dialing | NANPA PL-388 | Mandatory 10-digit dialing is imposed statewide, including area code 860 callers, in preparation for the future 959 overlay on the 860 NPA. This makes Connecticut one of the first states to mandate statewide 10-digit dialing before the second overlay was implemented. Source: NANPA — Connecticut Area Codes |
| 2014 | 959 overlay completed | CT PURA Docket | Area code 959 is placed in service as an overlay on area code 860, completing Connecticut's two-overlay-complex system. The state now operates with 203/475 in the southwest and 860/959 in the rest of the state. Source: Connecticut PURA |
County Coverage
Population-weighted county share based on aggregated ZCTA population (100% = total mapped population for area code 203).
| County | Population | Share |
|---|---|---|
| Fairfield, CT | 947,563 | 51.3% |
| New Haven, CT | 862,028 | 46.7% |
| Hartford, CT | 24,522 | 1.3% |
| Litchfield, CT | 13,185 | 0.7% |
Area Code 203 Family Tree
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All Descendants
Area code 203 was originally assigned in 01-Jan-1947 to serve CT. Over the years, it has generated 3 descendant area codes through a combination of geographic splits and overlays as demand for telephone numbers grew.
Call Context
This area code covers a geographic region across CT, including Bridgeport and surrounding communities.
Nearby Area Codes
Area codes geographically closest to 203.
Other Area Codes in Connecticut
Area codes that also serve Connecticut, linked for easy comparison.