<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2013) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2013) (Learn how and when to remove this template message) </Td> </Tr> <P> Area codes 410, 443, and 667 are telephone area codes serving the eastern half of the U.S. state of Maryland, including the Baltimore metropolitan area and the Eastern Shore . The 410 area code is the main area code, while the 443 and 667 codes are overlay codes . 443 and 667 were primarily used with cell phones and CLEC carriers such as Comcast or Cavalier Telephone when introduced but have since become universal in their carrier availability . </P> <P> Before these area codes were created, all of Maryland had been served by 301 since the institution of area codes in 1947, even though the state is home to two very large metropolitan areas--Baltimore and the Maryland suburbs of Washington, D.C. (area code 202). This made Maryland one of the most - populous states to be served by a single area code . However, by the late 1980s, 301 was on the verge of exhaustion due to the rapid growth of fax machine usage and the Baltimore and Washington suburbs . The supply of available numbers was further limited by the fact that most of the Maryland side of the Washington area shares an LATA with northern Virginia and the District itself . For over 40 years, it was possible to make a call between portions of the Washington area with only seven digits, since every number in 301 and northern Virginia's 703 was given a "hidden" number in the District's area code 202 . </P>

Where is area code 443 located in usa