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zipcodes.pro — AREA-CODE/203

203 area code

Area code 203 is in Connecticut. It covers Bridgeport, Stamford, New Haven and 122 other places: 161 ZIP codes in Fairfield, New Haven and Litchfield counties. Local time there is , Eastern Time. In service since 1947; 475 (2009) overlays it, so a number from there can have either code.

Time zone
Eastern
Largest city
New Haven
Overlays
475
In service since
1947
Rate centres
33
Prefixes assigned
784 (7,840,000 numbers)

Who calls from a 203 number

NANPA records the carrier each block of 203 numbers is assigned to. Of the 7.8 million 203 numbers assigned, 40% are with local phone companies (AT&T); 31% with mobile carriers (T-Mobile, Verizon Wireless and AT&T Mobility); 28% with cable, internet-calling, business and other carriers (PAETEC (Windstream) and Verizon Business); 2% with paging companies.

That is who the numbers were assigned to: people keep their number when they change carrier, so any one number may have moved since.

Carriers holding the most 203 numbers
CarrierKindShare
AT&TLandline38%
T-MobileMobile12%
Verizon WirelessMobile10%
AT&T MobilityMobile9%
PAETEC (Windstream)Cable, VoIP, other5%
Verizon BusinessCable, VoIP, other4%

An area code says where a number was issued, not where the caller is: people keep their numbers when they move, and caller ID can be set to show any number, which the FCC calls spoofing. If a call you did not expect asks for money or personal details, the FCC advises hanging up and calling the company back on a number you look up yourself. Unwanted calls can be reported to the FTC at ReportFraud.ftc.gov.

Places in area code 203

The 30 places with a telephone rate centre of their own using 203, largest first. Each links to its ZIP codes.

Places in area code 203
PlaceZIP codesPopulation
Bridgeport, CT 10 149,153
Stamford, CT 17 137,144
New Haven, CT 28 134,349
Waterbury, CT 16 114,869
Norwalk, CT 10 92,187
Danbury, CT 6 87,263
Meriden, CT 2 60,545
Fairfield, CT 3 58,698
Milford, CT 2 51,023
Wallingford, CT 4 44,498
Trumbull, CT 1 37,281
Naugatuck, CT 1 31,800
Cheshire, CT 3 28,904
Branford, CT 1 28,217
Westport, CT 4 27,583
Guilford, CT 1 22,067
Darien, CT 1 21,936
Wilton, CT 1 18,777
Madison, CT 1 17,657
Seymour, CT 1 16,889
Wolcott, CT 1 16,113
Greenwich, CT 3 14,792
Woodbury, CT 1 9,833
Redding, CT 1 8,779
Ridgefield, CT 2 6,970
Old Greenwich, CT 1 6,936
New Canaan, CT 1 6,896
Byram, CT — 4,633
Georgetown, CT 1 1,932
Newtown, CT 1 1,898

Nearby places using 203

These places have no rate centre of their own in NANPA's records; the nearest one uses 203. Near an area-code boundary that can be wrong for part of a town.

ZIP codes in area code 203

161 ZIP codes in 62 towns, by the town each is mailed to, largest first. Each links to its own page.

Where 203 numbers are issued

NANPA's rate centres with the most 203 prefixes (each prefix is 10,000 numbers), under NANPA's own abbreviated names.

Rate centres using area code 203
Rate centrePlacePrefixes
NEW HAVEN New Haven 145
STAMFORD Stamford 97
BRIDGEPORT Bridgeport 94
NORWALK Norwalk 60
DANBURY Danbury 54
WATERBURY Waterbury 52

Counties

The counties of its ZIP codes, most residents first, with how many of its ZIP codes each has.

Which code covers where you are now? What area code am I in? answers from your location.

Questions about area code 203

Where is area code 203?

Area code 203 is in Connecticut. It covers Bridgeport, Stamford, New Haven and 122 other places: 161 ZIP codes in Fairfield, New Haven and Litchfield counties.

What ZIP codes are in area code 203?

161 ZIP codes, by the town each is mailed to: Bridgeport (10, 06601 to 06699), Stamford (17, 06901 to 06927), New Haven (28, 06501 to 06540), Waterbury (16, 06701 to 06749) and 58 more towns. The full list is on this page.

What time zone is area code 203 in?

Eastern time.

Is a 203 number a mobile or a landline?

It can be either. 31% of 203 numbers are assigned to mobile carriers and 40% to local phone companies (NANPA, 2026-10-10); the rest are with cable, internet-calling, business and paging carriers. A number keeps its area code when it moves to another carrier.

What area codes overlay 203?

475. They cover the same area as 203, so a new number there can be given any of them.

Does a 203 number mean the caller is in Connecticut?

Not necessarily. An area code says where the number was first issued. People keep their numbers when they move or switch carriers, and calling software can show any number, so a 203 call can come from anywhere.

Other area codes in Connecticut

All 4 Connecticut area codes, by area, with the cities each covers

Source: NANPA NPA database, central office code and thousands-block assignments, 2026-10-10. Places are matched to NANPA's rate centres by name; see sources.

Cite this page

zipcodes.pro. “Area code 203.” Data release 2026-10-12. Retrieved 2026-10-20. https://zipcodes.pro/area-code/203

Underlying data is public domain or openly licensed — sources, vintages and licences.