The North American Numbering Plan (NANP) is a telephone numbering plan for twenty-five regions in twenty countries, primarily in North America and the Caribbean. This group is historically known as World Zone 1 and has the telephone country code 1. Some North American countries, most notably Mexico, do not participate with the NANP.
Area codes 314 and 557 are telephone area codes in the North American Numbering Plan (NANP) in the U.S. state of Missouri, serving the city of St. Louis and most of its inner-ring suburbs in neighboring St. Louis County. The numbering plan area is bordered to the west by area code 636, which serves St. Louis' outer suburbs to the west, south, and north. Across the Mississippi River to the east, 314 is adjacent to area code 618, which serves southern Illinois and most of Metro East. Area code 557 was added to the 314 numbering plan area on August 12, 2022, to form an overlay numbering plan.
Area codes 561 and 728 are telephone area codes in the North American Numbering Plan (NANP) for Palm Beach County in the U.S. state of Florida. 561 was created on May 13, 1996, in a split of area code 407. The numbering plan area (NPA) comprises nearly every major city in the county, the largest of which being West Palm Beach, Boca Raton, Wellington, Boynton Beach, Jupiter, Delray Beach, and Belle Glade. On March 10, 2023, area code 728 was added to the same numbering plan area to form an all-services distributed overlay.
Area codes 920 and 274 are telephone area codes in the North American Numbering Plan (NANP) for a large area of eastern Wisconsin. Area code 920 was created on July 26, 1997, in a split of area code 414, one of the original North American area codes of 1947. 274 was added to the same numbering plan area (NPA) on May 5, 2023 to create an area code overlay.
Area codes 740 and 220 are telephone area codes in the North American Numbering Plan (NANP) for the southeastern and central parts of Ohio. The numbering plan area (NPA) includes the cities of Athens, Belpre, Cadiz, Chillicothe, Circleville, Coshocton, Delaware, Gallipolis, Heath, Ironton, Jackson, Lancaster, Laurelville, Logan, Marietta, Marion, Mount Vernon, Nelsonville, Newark, Newcomerstown, Pataskala, Portsmouth, Rockbridge, Steubenville, Washington Court House, and Zanesville, Shadyside and the surrounding areas. It does not include the city of Columbus and rate centers in Franklin County which primarily use area code 614. Although it is Ohio's largest area code by geographic size, Southeastern Ohio is largely rural and has fewer residents overall than the rest of the state except in the areas near Columbus.
Area codes 202 and 771 are telephone area codes in the North American Numbering Plan (NANP) for Washington, D.C.
Area code 441 is the telephone area code in the North American Numbering Plan (NANP) for Bermuda. The numbering plan area (NPA) was created on 1 October 1995 in a split of area code 809.
Area code 268 is the telephone area code in the North American Numbering Plan (NANP) for Antigua and Barbuda.
Area code 246 is the telephone area code in the North American Numbering Plan (NANP) for Barbados. The sequence 246 spells BIM on an alpha-numeric telephone keypad, a nickname for the island.
Area codes 876 and 658 are telephone area codes in the North American Numbering Plan (NANP) for Jamaica.
Area codes 610, 484, and 835 are telephone area codes in the North American Numbering Plan (NANP) for the eastern and southeastern regions of Pennsylvania. The numbering plan area (NPA) includes regions to the west of Philadelphia and the cities Allentown, Bethlehem, and Reading. It includes much of the Delaware Valley, including almost all of Delaware County, most of the Philadelphia Main Line, and all of the Lehigh Valley.
Area code 660 is the telephone area code in the North American Numbering Plan (NANP) for the northern and western part of the U.S. state of Missouri. It was created on October 12, 1997, in a split of the 816 numbering plan area (NPA)
Area codes 256 and 938 are telephone area codes in the North American Numbering Plan (NANP) for North Alabama, as well as some eastern portions of the state. The two area codes form an overlay plan for the same numbering plan area. Area code 256 was created in 1998, and 938 was added in 2010.
Area codes 573 and 235 are telephone area codes in the North American Numbering Plan (NANP) for most of the eastern half of the U.S. state of Missouri outside the immediate St. Louis area, including the state capital of Jefferson City, as well as Columbia, Cape Girardeau, Hannibal, Rolla, and Sikeston. The largest cities are Columbia, home to the University of Missouri, and Jefferson City, the state capital.The numbering plan area (NPA) extends across half of the width of the state, with the northeastern tip near the northeastern corner of the state, the Lake of the Ozarks at the western tip and Doniphan as the southwestern tip. They also serves all of southeastern Missouri and areas adjacent to the Mississippi River. 573 was created on January 7, 1996, in a split of area code 314, which was limited to the St. Louis metropolitan area in Missouri, and 235 was added on March 24, 2024 as part of an overlay complex.
Area codes 303, 720 and 983 are telephone area codes in the North American Numbering Plan for the north-central portion of the U.S. state of Colorado. The numbering plan area comprises Denver and Boulder, as well as their surrounding suburbs, including Lakewood, Littleton, Longmont, Broomfield, Aurora, and Castle Rock. Area code 303 is the original area code, while area codes 720 and 983 were added to form an overlay complex for the area, meaning that the same geographic service area is served by all area codes and that ten-digit dialing is required for all calls made within the service area.
Area codes 816 and 975 are telephone area codes in the North American Numbering Plan (NANP) for most of the Missouri side of the Kansas City metropolitan area, the St. Joseph area, and all or part of 15 surrounding counties in northwestern Missouri. The numbering plan area originally comprised most of the northern and western two-thirds of the state, bordering with Arkansas, Illinois, Iowa, Kansas, Nebraska, and Oklahoma, but has been reduced to a ribbon bordering Kansas. 816 is one of the original 86 area codes created in 1947. The numbering plan area was converted to an overlay complex with area code 975 in 2023.
Area code 636 is a telephone area code in North American Numbering Plan (NANP) for the east-central part of the U.S. state of Missouri, comprising mainly the western suburbs of St. Louis. It includes parts of Chesterfield and Fenton in St. Louis County, and all of St. Charles, Jefferson, and Warren counties, all of Franklin County with the exception of Sullivan, as well as the towns of High Hill and Jonesburg in Montgomery County and the southern portion of Lincoln County. It was created in 1999 in an area code split from area code 314, which was one of the original North American area codes of 1947.
In the North American Numbering Plan (NANP), interchangeable NPA and central office codes constituted a change in numbering plan design and policy, to mitigate exhaustion of the numbering resources of the ten-digit telephone numbers used in the closed numbering plan of the NANP.
