telecommunications Telecommunication is the transmission of information by various types of technologies over wire, radio, optical, or other electromagnetic systems. It has its origin in the desire of humans for communication over a distance greater than that fe ...

, an area code split is the practice of introducing a new telephone

area code A telephone numbering plan is a type of numbering scheme used in telecommunication to assign telephone numbers to subscriber telephones or other telephony endpoints. Telephone numbers are the addresses of participants in a telephone network, rea ...

by geographically dividing an existing

numbering plan area 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 international calling ...

(NPA), and assigning area codes to the resulting divisions, but retaining the existing area code only for one of the divisions. The purpose of this practice is to provide more central office prefixes, and therefore more

telephone number A telephone number is a sequence of digits assigned to a landline telephone subscriber station connected to a telephone line or to a wireless electronic telephony device, such as a radio telephone or a mobile telephone, or to other devices f ...

s, in an area with high demand for telephone services, and prevent a shortage of telephone numbers. An increasing demand for telephone numbers has existed since the development of automatic telephony in the early 20th century, but was spurred especially since the 1990s, with the proliferation of fax machines, pager systems, mobile telephones, computer modems, and finally

smart phone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, which ...

s. When an area code split is implemented, the telephone numbers in the affected area are typically changed to a new area code only, but this still requires the printing of new stationery, advertisements, and signage for many customers, and the dissemination of the new area code to family, friends, and customers. Computer systems, and telephone equipment may require updates in address books, and for speed dialing. 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.AT&T, ''Notes on the Network'' (1975), Section 2 Furthermore, the new boundaries are drawn in a manner that minimizes splitting communities and should coincide with political subdivision where practical. Other geographic features, such as rivers and bodies of water, mountain ranges, or highways may serve as guides for boundary placements. Tributary toll telephone routes should also not be unduly cut, so prevent rerouting to new toll center switching systems. The area that retains the existing area code is typically the largest, or historically more established or developed place.

Area code overlays

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 mid-1990s, the

North American Numbering Plan 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 international callin ...

Administrator introduced another method for exhaustion relief, the

area code overlay Area is the quantity that expresses the extent of a region on the plane or on a curved surface. The area of a plane region or ''plane area'' refers to the area of a shape or planar lamina, while '' surface area'' refers to the area of an open s ...

. This method assigns multiple area codes to the same numbering plan area, so that existing subscribers can keep established telephone numbers. Only new accounts and extra lines receive telephone numbers with the new area code. This method requires

ten-digit dialing Ten-digit dialing is a telephone dialing procedure in the countries and territories that are members of the North American Numbering Plan (NANP). It is the practice of including the area code of a telephone number when dialing to initiate a telep ...

for customers of both area codes, even for local calls. Since 2007, most territories use overlays for mitigating numbering shortages. Most area code relief plans today do not even consider splits as relief options, limiting options to overlay plans.https://www.nationalnanpa.com/reports/2021_NANPA_Annual_Report.pdf

References

{{reflist Telephone numbers

Area code overlays

See also

References