WHAT YOU NEED TO KNOW
Area code 443 serves Maryland statewide, including Baltimore, Annapolis, Columbia, and Towson. Established in 1997 as an overlay to area code 410, it covers approximately 6.2 million residents across the entire state. The code operates alongside 410 and 667, making it one of three codes serving the Baltimore metro and broader Maryland region.
- Population: ~6.2 million residents statewide
- Overlay: Overlay: 410 and 667
- Dialing: 10-digit dialing required
- Source Type: Local geographic code
Geographic Coverage
Area code 443 covers the entire state of Maryland, spanning Baltimore City, Baltimore County, Anne Arundel County, Howard County, Prince George's County, Montgomery County, Frederick County, and Washington County, among others. Key cities include Baltimore, Annapolis, Columbia, Towson, Ellicott City, Bowie, Glen Burnie, Catonsville, Pikesville, Owings Mills, Rockville, Gaithersburg, Frederick, and Hagerstown. Because 443 is a statewide overlay, it does not have distinct geographic boundaries separate from area codes 410 and 667.
Population and Business Context
Maryland supports a diverse economic base spanning federal government contracting, healthcare, cybersecurity, biotechnology, finance, and education. The Baltimore metro anchors much of the state's commercial activity, with major employers in the Johns Hopkins health and university system, the Port of Baltimore, and numerous defense agencies. The Washington, D.C. suburbs in Montgomery and Prince George's counties add a large concentration of professional services and technology firms to the 443 service area.
Area Code History
Area code 443 was introduced in 1997 as an overlay to the existing area code 410, which had served Maryland since 1991 when it was split from the original 301 code. The overlay was necessary due to growing demand for telephone numbers driven by mobile phones, fax machines, and internet dial-up services. A second overlay, area code 667, was subsequently added in 2012 to address continued number exhaustion across the state.
How to Dial
All calls within Maryland, including local calls between numbers sharing the same area code, require 10-digit dialing. This means you must dial the full area code plus the 7-digit local number for every call, whether local or long-distance. The 10-digit requirement applies to all three Maryland area codes: 410, 443, and 667. Callers dialing from outside Maryland must use 1 followed by the full 10-digit number.
Need a 443 Number for Your Baltimore Metro Business?
Businesses operating in Maryland can claim a local 443 tracking number through Convirza. Whether your customers are in Baltimore, Annapolis, Columbia, or anywhere else across the state, a local area code builds trust and keeps your marketing measurable. Convirza provisions trackable local numbers in any North American area code, including 443, with no hardware required. Every call to your 443 number gets scored, recorded, and source-attributed using dynamic number insertion (DNI), so you know exactly which campaigns drive phone leads. Calls route to any team, location, or device you choose. You get full visibility into caller behavior, campaign performance, and conversation quality from a single dashboard.
750+ customers · 25 years of call data