Area code split

Since area code splits have substantial impact in the involved communities, and involve substantial cost in telephone plant and exchange equipment, they are planned carefully well ahead of implementation with the intent that an area is not again affected by a subsequent realignment for at least a decade.[1] The new boundaries of the numbering plan areas are drawn in a manner that minimizes splitting communities and should coincide with political subdivision where practical.[1] Other geographic features, such as rivers and bodies of water, mountain ranges, or highways may serve as guides for boundary placements.Not withstanding the desire for long-term stability of the local numbering plan and customer understanding, rapid growth in some areas has resulted in many splits within just a few years.As a result, in the early 1990s, the North American Numbering Plan Administrator (NANPA) introduced another method for exhaustion relief: the area code overlay.
telecommunicationsarea codenumbering plan areacentral office prefixestelephone numberssmart phonesClass-4 toll switching centerOverlay complexNorth American Numbering Plan Administratorten-digit dialingFlash-cutNumber poolingPermissive dialingSeven-digit dialingTelephone exchange