Where is area code 203?
NANPA assigns 203 to Connecticut. The source report does not provide city-level coverage for this record, so this page does not guess a particular city. Browse other codes in Connecticut
Verified area-code information
203 Area Code
203 is an in-service United States area code assigned to Connecticut. It identifies a numbering region, not a caller’s current location.
Official Numbering RegionVerified NANPA Assignment
ConnecticutArea Code 203
Country: United States•Time Zone: Eastern•Overlays: 475•In Service: 01-Jan-1947
- Numbering country
- United States
- Area-code type
- Geographic
- Numbering region
- Connecticut
- Time-zone information
- Eastern
- In service since
- 01-Jan-1947
View the official area-code maps ↗. Maps show numbering areas, not a caller’s location.
Time zones associated with 203
NANPA lists Eastern for this numbering area. These are numbering-region time zones, not a caller’s current location.
Eastern time
An area code can span more than one time zone. Local daylight-saving rules may differ.
What area codes overlay 203?
The NANPA source lists 475 in the same overlay complex. An overlay can serve the same broad numbering area; individual numbers still do not prove where a person is.
How do you dial a 203 number?
Use the North American country calling code +1 followed by the three-digit area code and seven-digit local number. For example, write the pattern as +1 203 XXX XXXX. Local dialing rules and charges depend on your location and provider. Check a supported dialing format or check NANPA’s 10-digit dialing list.
Assigned prefixes in 203
NANPA’s US report listed 784 assigned prefixes on 2026-09-29. These are code assignments, not a count of active phone numbers or proof of a caller’s current carrier. Search any US area code and prefix.
Top rate-center labels by assigned prefixes
| Rate center | Assigned prefixes |
|---|---|
| NEW HAVEN | 145 |
| STAMFORD | 97 |
| BRIDGEPORT | 94 |
| NORWALK | 60 |
| DANBURY | 54 |
Top listed companies by assigned prefixes
| Assignment company | Assigned prefixes |
|---|---|
| SOUTHERN NEW ENGLAND TELCO DBA FRONTIER COMM OF CT | 338 |
| CELLCO PARTNERSHIP DBA VERIZON WIRELESS - CT | 61 |
| NEW CINGULAR WIRELESS PCS, LLC - DC | 52 |
| OMNIPOINT COMMUNICATIONS, INC. - CT | 47 |
| LEVEL 3 COMMUNICATIONS, LLC - CT | 41 |
203 prefix lookup
784 assigned prefixes are listed for this area code. Search NANPA’s US central-office code assignments. The listed company and rate center describe an assignment; number portability means they cannot identify the current carrier, subscriber, or caller.
The area-code file loads when you search. The three-digit prefix stays in your browser.
Check a number with area code 203
Enter the full ten-digit number to see its structure and formatting. The check stays in your browser.
Check a 203 number
Enter a 10-digit +1 North American number. We check its structure and area-code record, not the caller’s identity or whether the line is active.
Processed locally in your browser. Nothing you enter is sent to OfficialAreaCode or saved.
Received an unfamiliar call?
The displayed number may be spoofed. Do not rely on an area code as proof of caller identity. If the caller claims to represent a business, end the call and contact that business using a number you found independently.
Common questions about 203
What time zone is area code 203 in?
203 is assigned to Connecticut, and the NANPA record associates it with Eastern time. A phone number does not reveal its owner’s current time zone. The clock above uses a representative time zone for the numbering area.
Does 203 mean the caller is in Connecticut?
No. An area code is an assignment, and a person can travel, move, use internet calling, or display a spoofed number.
Can this page identify who called?
No. OfficialAreaCode has no live subscriber directory or spam-report database.