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Interchangeable NPA Codes
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. Interchangeable NPA and central office codes are codes that permit any of the ten numerals in the middle position of the area code and the central office code, which both are three-digit numbers.AT&T Network Planning Division, ''Notes on the Network'', Section 2 (1980) This change in numbering format was implemented first for central office codes by 1973, which eliminated the restriction in the middle digit (''2'' to ''9'') to also permit ''0'' and ''1''. The middle position of the area code could only be ''0'' and ''1''. In 1995, this restriction for area codes was lifted as well, creating interchangeable NPA codes. History and background The ten-digit telephone numbers of the NANP consist of a three-digit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 calling code ''1''. Some North American countries, most notably Mexico, do not participate in the NANP. The NANP was originally devised in the 1940s by the AT&T Corporation, American Telephone and Telegraph Company (AT&T) for the Bell System and the independent telephone operators in North America. The goal was to unify the diverse local numbering plans that had been established in the preceding decades and prepare the continent for direct-dialing of calls by customers without the involvement of telephone operators. AT&T continued to administer the numbering plan until the breakup of the Bell System, when administration was delegated to the North American Numbering Plan Administrator (NANPA), a service that has been procured from the private sect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Closed Numbering Plan
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, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks. For public numbering systems, geographic location typically plays a role in the sequence of numbers assigned to each telephone subscriber. Many numbering plan administrators subdivide their territory of service into geographic regions designated by a prefix, often called an area code or city code, which is a set of digits forming the most-significant part of the dialing sequence to reach a telephone subscriber. Numbering plans may follow a variety of design strategies which have often arisen from the historical evolution of individual t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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, reachable by a system of destination code routing. Telephone numbering plans are defined in each of the administrative regions of the public switched telephone network (PSTN) and in private telephone networks. For public numbering systems, geographic location typically plays a role in the sequence of numbers assigned to each telephone subscriber. Many numbering plan administrators subdivide their territory of service into geographic regions designated by a prefix, often called an area code or city code, which is a set of digits forming the most-significant part of the dialing sequence to reach a telephone subscriber. Numbering plans may follow a variety of design strategies which have often arisen from the historical evolution of individu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seven-digit Dialing
Seven-digit dialing is a telephone dialing procedure customary in some territories of the North American Numbering Plan (NANP) for dialing telephone numbers in the same numbering plan area (NPA). NANP telephone numbers consist of ten digits, of which the leading three are the area code. In seven-digit dialing it is not necessary to dial the area code. The procedure is also sometimes known as ''local format'' or ''network format''. History Originally, telephone exchanges consisted of manual switchboards operated by switchboard operators. Telephone numbers had typically two to four digits, depending on the size of the community. As the number of subscribers grew, multiple exchanges served individual neighborhoods of large cities. Multiple exchanges were identified by a central office name and typically four digits, such as "Pennsylvania 5000". A rural telephone number, often party line, had often up to four digits plus a letter or letter and digits to indicate which of the multiple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Common Control
In telecommunications, common control is a principle of switching telephone calls in an automatic telephone exchange that employs shared control equipment which is attached to the circuit of a call only for the duration of establishing or otherwise controlling the call. Thus, such control equipment need only be provided in as few units to satisfy overall exchange traffic, rather than being duplicated for every subscriber line. In contrast, ''direct control'' systems have subsystems for call control that are an integral part of the switching network. Strowger exchanges are usually direct control systems, whereas crossbar, and electronic exchanges (including all stored program control systems) are common control systems. Common control is also known as indirect control or register control. History Early semi-mechanical installations with common control components existed, for example rotary systems in Sweden and France in 1915, and the first panel switches in Newark, New Jerse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Direct Distance Dialing
Direct distance dialing (DDD) is a telecommunication service feature in North America by which a caller may, without operator assistance, call any other user outside the local calling area. Direct dialing by subscribers typically requires extra digits to be dialed as prefixes to the directory telephone number of the destination. International Direct Distance Dialing (IDDD) extends the system beyond the geographic boundaries of the North American Numbering Plan (NANP). History The first direct-dialed long-distance telephone calls were possible in the New Jersey communities of Englewood and Teaneck. Customers of the ENglewood 3, ENglewood 4 and TEaneck 7 exchanges, who could already dial telephone numbers in the New York City area, could place calls to eleven major cities across the United States by dialing the three-digit area code and the seven-digit directory number. Local telephone numbers still consisted of the first two letters of the central office name and five digits. On ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Area Code 905
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 surface or the boundary of a three-dimensional object. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat. It is the two-dimensional analogue of the length of a curve (a one-dimensional concept) or the volume of a solid (a three-dimensional concept). The area of a shape can be measured by comparing the shape to squares of a fixed size. In the International System of Units (SI), the standard unit of area is the square metre (written as m2), which is the area of a square whose sides are one metre long. A shape with an area of three square metres would have the same area as three such squares. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Area Code 416
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 surface or the boundary of a three-dimensional object. Area can be understood as the amount of material with a given thickness that would be necessary to fashion a model of the shape, or the amount of paint necessary to cover the surface with a single coat. It is the two-dimensional analogue of the length of a curve (a one-dimensional concept) or the volume of a solid (a three-dimensional concept). The area of a shape can be measured by comparing the shape to squares of a fixed size. In the International System of Units (SI), the standard unit of area is the square metre (written as m2), which is the area of a square whose sides are one metre long. A shape with an area of three square metres would have the same area as three such squares. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Area Code 334
Area code 334 is a telephone area code in the North American Numbering Plan (NANP) for southeastern Alabama. It was created on January 15, 1995, in an area code split from area code 205. and was the first new area code in Alabama since the implementation of area codes in 1947. To permit a transition period for the reconfiguration of equipment, such as computers and fax machines, use of area code 205 continued in the 334 region through May 13, 1995. The numbering plan area (NPA) comprises the Montgomery, Auburn-Opelika, and Dothan metropolitan areas, as well as Phenix City and the Alabama side of the Columbus, Georgia metro area. The original 334 territory included the southern half of Alabama. Area code 251 was subsequently split from 334 in 2001 for southwest Alabama, including Mobile. Area code 334 was the first interchangeable NPA code, not having the middle digit as ''0'' or ''1'', officially preceding Washington area code 360 by one minute. Exhaustion projections ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Area Code 360
Area code 360 is the telephone area code for western Washington state outside metropolitan Seattle. It began service on January 15, 1995. The numbering plan area (NPA), which encompasses all of western Washington outside urban King, Pierce, and Snohomish counties and Bainbridge Island, was previously part of area code 206. Area codes 360 and 334 (Alabama), which began service on the same day, were the first two area codes in the North American Numbering Plan with a middle digit other than 0 or 1. The served area consists of two sections. The larger, western portion stretches from the Strait of Juan de Fuca to the Oregon border, while the portion on the east shore of Puget Sound stretches from the border with British Columbia, Canada, almost to Everett. This configuration came when residents of several Seattle exurbs protested being moved into 360. In response, US West put some of them back in 206. However, 206 was on the brink of exhaustion even after the creation of 360, an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
