"system used for assigning" . "Area code(s)" . "numbering plan indicator" . . "Telephone_numbering_plan#Area_code" . "Telephone numbering plan" . "numbering plan" . "closed" . "prefix" . "Numbering Plan" . "Telephone numbering plan#Area code" . "Closed" . "numbering plans" . . "Telephone_numbering_plan#Local_number" . "closed telephone dialing plan" . "phone dialing codes" . . . . "geographic phone code" . "open dialing plan" . "Numbering plans by country" . "telephone numbering plan" . "area-code" . "Telephone numbering plan#Closed dialing plans" . "Phone code" . "Telephone numbering plan#Private numbering plan" . . . "Area Code system" . . . . "closed numbering plan" . "Telephone code" . "Telephone numbering plan#Open dialing plans" . "Telephone numbering plan#Variable-length dialing" . . "dial plan type" . "Area Codes" . "Telephone Area Code" . "Area Code(s)" . "Calling code" . "area codes" . "Open" . "closed numbering system" . "telephone code" . "Telephone area code" . "full number dialing plan" . "dialling code" . "number" . "subscriber number" . "423" . "Telephone numbering plan" . "closed dialing plan" . "country code" . "optional" . "Area codes" . "telephone numbering" . "Area code" . "full numbering scheme" . . "telephone area code" . "Area Code" . "area code" . "STD code" . "telephone numbering plan#Private numbering plan" .