The Maryland Public Service Commission has learned that an additional area code will be implemented across several areas of the state next year. A 667 area code will be used starting March 24. The commission said the remaining numbers in the 410 and 443 area codes are expected to be exhausted by early 2012. The new area code will be assigned to all or parts of the following areas in Maryland beginning in March: Anne Arundel County, Baltimore County, Baltimore City, Calvert County, Caroline County, Carroll County, Cecil County, Dorchester County, Harford County, Howard County, Kent County, Queen Anne’s County, Somerset County, Talbot County, Wicomico County and Worcester County. Callers will continue to dial the area code before the number, and existing 410 and 443 telephone numbers will not be affected by the new area code, the commission said. The previous implementation of a new area code occurred in 1997, with the addition of area codes 240 and 443.