--- title: "Area code 443: Maryland, United States" url: "https://lookvalid.com/area-code/443.md" canonical_url: "https://lookvalid.com/area-code/443" last_updated: "2026-10-23" type: "reference" summary: "Area code 443 serves Maryland, United States. Number formats, numbering rules, a live phone validator and the other codes in Maryland." --- # Area code 443: Maryland, United States Area code 443 serves Maryland, United States. Number formats, numbering rules, a live phone validator and the other codes in Maryland. NANPA lists 785 central office codes (prefixes) in use in area code 443, held by 25 holders across 81 rate centers. Paetec Itel holds the most prefixes, 153 (19%). 89% of the prefixes are pooled, which means their thousands-blocks can belong to different companies. The FCC unwanted-call data has 4,476 complaints on file for 3,050 numbers in 443, most often filed as "Unwanted Calls". These are consumer reports, not findings. ## Facts - In service since: 1997-06-01 - Time zone: Eastern (E) - Assigned overlays: 410 (1991-10-06), 667 (2012-03-24) - Prefixes in use: 785 - Pooled prefixes: 701 (89%) - Rate centers: 81 - Companies holding prefixes: 25 - Assignment dates on file: 2001-01-10 to 2023-11-21 (299 prefixes) - ZIP codes in its places: 110 ## Rate centers | Rate center | Prefixes | Share | | --- | --- | --- | | BALTIMORE | 185 | 24% | | ANNAPOLIS | 39 | 5% | | TOWSON | 33 | 4% | | COLUMBIA | 31 | 4% | | GLENBURNIE | 26 | 3% | | CATONSVL | 22 | 3% | | PIKESVILLE | 21 | 3% | | SALISBURY | 20 | 3% | | 73 other rate centers | 408 | 52% | ## Carriers | Holder | Prefixes | Share | | --- | --- | --- | | Paetec Itel | 153 | 19% | | Verizon Wireless | 121 | 15% | | Omnipoint Communications Cap Operations | 94 | 12% | | New Cingular Wireless PCS | 71 | 9% | | Level 3 Communications | 69 | 9% | | Verizon Maryland | 55 | 7% | | 19 other carriers | 222 | 28% | A prefix holder is the company a code was assigned to, not necessarily a number's current carrier, because numbers can be ported to another company. ## History - 1991-10-06: Area code 410, named as the parent of 443 in the NANPA report, was in service. - 1997-06-01: Area code 443 went into service. - 2012-03-24: Area code 667 went into service as an overlay in the same area as 443. ## Nearest area codes The area codes closest to 443, measured between the centers of the ZIP code places they serve, are 301 (about 44 miles), 302 (about 50 miles), 571 (about 59 miles), 703 (about 59 miles) and 223 (about 71 miles). ## ZIP codes 110 ZIP codes fall in places that have a rate center in this area code. The places with the most are Baltimore, MD (42 ZIP codes), Annapolis, MD (8 ZIP codes) and Towson, MD (5 ZIP codes). A ZIP code and an area code are unrelated systems, so a ZIP code can sit in more than one area code and an area code spans many ZIP codes. ## Complaints on file 4,476 complaints for 3,050 numbers. Numbers whose latest complaint falls in each year: - 2023: 154 - 2024: 183 - 2025: 162 ## Questions ### Where is area code 443? NANPA assigns area code 443 to Maryland, United States. ### In which state does area code 443 sit? Maryland. 443 is one of 6 area codes the NANPA table assigns to the state. ### Which places does area code 443 cover? The places with the most ZIP codes among the rate centers in 443 are Baltimore, MD, Annapolis, MD and Towson, MD. The rate center list on this page shows all of them. ### Who owns area code 443? NANPA assigns area codes. Within 443, Paetec Itel holds the most prefixes, 153 prefixes or 19%. ### Which time zone does 443 use? The NANPA NPA report lists the time zone for 443 as Eastern (E). ### What year did 443 enter service? The NANPA NPA report gives an in-service date of 1997-06-01, so 443 has been in use since 1997. ### Does area code 443 have an overlay? Yes. 410 (in service 1991-10-06) and 667 (in service 2012-03-24) share the same area with 443, so numbers from all of them are local to each other. ### Which area codes are nearest to 443? The area codes closest to 443, measured between the centers of the ZIP code places they serve, are 301 (about 44 miles), 302 (about 50 miles), 571 (about 59 miles), 703 (about 59 miles) and 223 (about 71 miles). ### How many prefixes does area code 443 have? NANPA's report dated 2026-10-17 lists 785 prefixes in service in 443, spread over 81 rate centers and 25 holders. ### Are there complaints about 443 numbers? The FCC data on file has 4,476 complaints for 3,050 numbers in 443. They are unverified consumer reports. A number with no complaints on file is not proven safe. Sources: NANPA central office code report dated 2026-10-17; NANPA NPA report dated 2026-10-18; FCC unwanted-call complaints, data fetched 2026-10-17; ZIP code places from GeoNames (CC BY 4.0).