Numbering plan areas and area codes of Pennsylvania (blue).
The Commonwealth of Pennsylvania is divided into seven distinct geographic numbering plan areas in the North American Numbering Plan, and served by a total of fifteen area codes. All NPAs have at least two area codes, but the large metro area of Philadelphia has three, as well as the large region surrounding it in the southeast of the state.
In 1947, the American Telephone and Telegraph Company divided Pennsylvania into four numbering plan areas and assigned one distinct area code to each. Since 1995, several relief actions in form of area code splits and overlays have expanded the number of area codes. As a result, all numbering plan areas are overlay complexes and ten-digit dialing is mandatory statewide.
