667 Area Code: A Complete Guide to Baltimore and Maryland's Eastern Shore

Quick answer: Area code 667 is a telephone overlay covering Baltimore City, Baltimore County, and Maryland's Eastern Shore — sharing the exact same territory as area codes 410 and 443. Activated on March 24, 2012, it is the third code layered onto a region that has used a single boundary since 1991. The territory operates in the Eastern Time Zone, and ten-digit dialing has been mandatory since the 443 overlay arrived in 1997.

Area code 667: Maryland's third overlay for Baltimore and the Eastern Shore

Area code 667 does not mark out its own patch of Maryland — it is layered directly on top of the territory already served by 410 and 443. All three codes cover the same footprint: Baltimore City, the surrounding suburban counties, and the Chesapeake Bay's Eastern Shore.

This all-services overlay means new phone numbers issued anywhere in the region can carry a 410, 443, or 667 prefix, regardless of which one a caller's neighbor happens to have. No existing number changed when 667 launched — it simply expanded the pool of numbers available as Baltimore's population of phones, from smartphones to VoIP business lines, kept climbing.

Landlines, wireless carriers, and business VoIP providers all draw from the same shared 410/443/667 pool today, so it is common for members of the same household or the same office to hold numbers across two or even all three prefixes without any change in service, coverage, or call quality.

Pairing a 667 number with a 471 area code Northern Virginia DC Metro presence creates a natural Baltimore–Washington corridor, connecting Maryland's port and biotech economy with the federal contracting and technology markets clustered around the nation's capital.

Baltimore, Columbia, and the Eastern Shore: cities inside the 667 territory

The 667 territory spans Baltimore City and eight surrounding counties, stretching from the Baltimore Beltway across the Chesapeake Bay Bridge to the Eastern Shore. Nearly two-thirds of Maryland's population lives inside this single overlay footprint, making it one of the most numbers-dense telephone territories on the East Coast.

Baltimore City and metro core:

• Baltimore City — Maryland's largest city, home to the Inner Harbor, Johns Hopkins University and Hospital, and the Port of Baltimore
• Towson (Baltimore County) — The county seat, anchored by Towson University and a dense retail and professional corridor
• Dundalk, Essex, Catonsville, Parkville — Established Baltimore County suburban communities ringing the city

Suburban counties:

• Columbia and Ellicott City (Howard County) — Planned communities and a major biotech, defense-contracting, and professional services base near Fort Meade
• Annapolis, Glen Burnie, Severna Park (Anne Arundel County) — Maryland's state capital and the communities surrounding Fort George G. Meade
• Bel Air (Harford County) — Anchoring the corridor toward Aberdeen Proving Ground

Eastern Shore:

• Salisbury (Wicomico County) — The Eastern Shore's largest city and headquarters of Perdue Farms
• Easton (Talbot County) and Chestertown (Kent County) — Historic Chesapeake Bay towns supporting tourism and agriculture
• Ocean City (Worcester County) — Maryland's premier Atlantic beach resort destination
• Cambridge (Dorchester County) — A working waterfront city on the Choptank River supporting the Eastern Shore's seafood and boatbuilding trades

One region, three codes: how 410, 443, and 667 came to share Maryland

Area code 301 originally covered the entire state of Maryland when the North American Numbering Plan launched. As the state's population grew, NANPA split off area code 410 in 1991, carving out Baltimore City, its suburbs, and the Eastern Shore into a dedicated code while 301 remained with the DC suburbs and western Maryland.

That split was meant to last for years, but the rapid rise of cell phones and pagers through the mid-1990s pushed 410 toward exhaustion within only five years. Rather than force another split — which would have required residents on either side of a new boundary to change numbers a second time — the Maryland Public Service Commission approved an overlay. Area code 443 launched on July 1, 1997, making ten-digit dialing mandatory across the entire 410 territory for the first time.

By 2011, continued growth in mobile and business VoIP lines meant the combined 410/443 territory was again running low on available prefixes. To spare more than four million residents yet another disruption, a third overlay, area code 667, entered service on March 24, 2012, adding roughly 24 million new numbers to the same footprint.

It was the 359th area code assigned in North America, and it remains the only Maryland code with no dedicated geographic boundary of its own — every 667 number is, by definition, also a Baltimore or Eastern Shore number.

Ten-digit dialing across the 410, 443, and 667 territory

Because three area codes share one territory, every call placed within the region — even between two phones sitting on the same block — must include the area code.

Time zone: The entire 667 territory observes Eastern Time — the same zone as Washington DC, New York, and Philadelphia. Businesses coordinating between Baltimore and the Eastern Shore never need to account for a time difference, since both sides of the Chesapeake Bay Bridge share one clock. That single time zone also keeps scheduling simple for call centers and customer support teams that route inbound traffic to a 667 number from elsewhere in the country.

Building a Maryland presence with a 667 area code number

A 667 area code number places a business inside one of the mid-Atlantic's densest concentrations of healthcare research, federal contracting, port logistics, and Eastern Shore agriculture — while still reading as a genuinely local number to Baltimore-area callers, since it shares the same footprint as 410 and 443.

Key reasons to establish a 667 area code number:

• Johns Hopkins University and Hospital — A global leader in medical research and academic medicine, anchoring a vast network of biotech startups, medical device firms, and healthcare service providers across Baltimore
• Port of Baltimore — One of the busiest US ports for automobiles and farm equipment, supporting a deep logistics, shipping, and warehousing economy
• Fort George G. Meade — Home to the National Security Agency and US Cyber Command, driving demand for cybersecurity, IT, and defense-contracting firms across Anne Arundel and Howard counties
• Perdue Farms and Eastern Shore agriculture — Headquartered in Salisbury, Perdue anchors a poultry, agriculture, and food-processing economy spanning the entire Eastern Shore
• Under Armour and T. Rowe Price headquarters — Under Armour's global apparel business anchors Baltimore's Locust Point waterfront, while T. Rowe Price, one of the largest independent asset managers in the country, roots a substantial financial services sector downtown
• UCaaS virtual Maryland presence — Businesses targeting Baltimore's healthcare, defense, or port markets from outside Maryland can establish immediate local credibility through a Unified Communications as a Service (UCaaS) platform, provisioning a 667 number with cloud-hosted voice, video, messaging, and analytics routed to any device worldwide; pairing a 667 number with a 617 area code Boston presence creates a natural East Coast healthcare and biotech corridor, connecting Johns Hopkins with the Kendall Square research cluster

Comptroller impersonation and other 667 area code scam calls

Area code 667 is a legitimate telephone prefix serving millions of Maryland residents and businesses — but scammers actively spoof 667 numbers to appear local to Baltimore and Eastern Shore residents.

Most frequently reported 667 scam types:

• Fake Comptroller and IRS impersonation — Callers claim to represent the Maryland Comptroller's office or the IRS, threatening immediate imprisonment for alleged tax evasion unless payment is wired instantly
• Extended car warranty robocalls — Prerecorded messages claim a vehicle's warranty is expiring, pushing targets toward high-pressure sales calls for coverage that is rarely delivered
• Debt relief and credit repair fraud — Callers offer to erase debt or repair credit scores in exchange for upfront fees, then vanish without providing any service
• Social Security suspension scams — Automated calls claim a Social Security number has been suspended due to suspicious activity, demanding a callback to "verify" identity or pay a fee

Staying protected: The IRS, Social Security Administration, and Maryland Comptroller's office never initiate unsolicited calls demanding immediate payment. Report suspected 667 scam calls to the FTC at reportfraud.ftc.gov and to the Maryland Attorney General at (410) 528-8662.

The 667 area code in numbers

• Area code 667 overlays 410 and 443 across Baltimore City, Baltimore County, and Maryland's Eastern Shore
• It was activated on March 24, 2012, as the region's third overlay code
• Ten-digit dialing is mandatory for every call, local or long-distance, since the 1997 443 overlay
• The entire territory observes Eastern Time — aligned with Washington DC, New York, and Philadelphia
• Major economic anchors include Johns Hopkins, the Port of Baltimore, Fort George G. Meade, Under Armour, and Perdue Farms
• The most reported 667 scam types are fake Comptroller/IRS impersonation, car warranty robocalls, debt relief fraud, and Social Security suspension scams

Frequently asked questions