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Maryland is currently using four area codes. Maryland is utilizing two area code overlay plans, often called overlay
complexes. Maryland currently has two area codes, 227 and 667, which have been assigned to provide numbering relief but are not yet in service.
Maryland originally had one area code, 301, when the
numbering system was established in 1947. It was not until forty-four years later in 1991 that Maryland experienced sufficient growth in population and telephone use to need an additional area code. To meet
this increase in demand area code 301 was split to form area code 410. Later in 1997 area code 301 was overlaid with area code 240 and area code 410 was overlaid with area code 443. These changes resulted in
four area codes being utilized in Maryland by 1997.
Changes and History of Maryland Area Codes:
01/01/1947
Area code 301 was put into service. In 1991 area code 301 was split to form area
code 410. In 1997 area codes 301 was overlaid with area code 240.
10/06/1991
Area code 410 was put into service. Area code 410 was created from a split of area code 301. In 1997 area code 410 was
overlaid with area code 443.
06/01/1997
Area code 240 was put into service. Area code 240 is an overlay of area code 301.
06/01/1997
Area code 443 was put into service. Area code 443 is
an overlay of area code 410.
not in service
Area code 227 is proposed as an overlay of area code 240 and 301 but is not yet in service. When area code 227 is implemented the new overlay plan, or
complex, will be 301/240/227.
not in service
Area code 667 is proposed as an overlay of area code 443 but is not yet in service. When area code 667 is implemented the new overlay plan, or complex,
will be 410/443/667. |
