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In the administration of the North American Numbering Plan, central office code protection is a numbering policy for maintaining local seven-digit dialing in communities that extend on both sides of the boundary line between multiple numbering plan areas (NPAs), such as in cross-border towns on state lines.
Nigerian ports authority, CMS. The Nigerian Ports Authority (NPA) is a federal government agency that governs and operates the ports of Nigeria.The major ports controlled by the NPA include: the Lagos Port Complex and Tin Can Island Port in Lagos; Calabar Port, Delta Port, Rivers Port at Port Harcourt, and Onne Port.
From 1947 to 1995, all NPA codes were distinguished with the digits 0 or 1 in the middle position. This provided the traditional format N 0/1 X, where N is any digit from 2 to 9, and X is any of the ten numerals. This format provided a set of 160 combinations, but only 144 were in use for geographic NPA codes.
NANP telephone numbers are formally rendered as NPA-NXX-XXXX, but (NPA) NXX-XXXX is common, as are others forms of punctuation. The parentheses were used originally to indicate that the area code was not necessary for local dialing. The NPA-part of the number has the formal format NXX, since 1995 identical to the format of central office codes.
The area code designates a numbering plan area (NPA) which is a geographic division of the numbering plan's entire service area, based principally on the boundaries of U.S. states, Canadian provinces, and smaller countries and territories. Many states and provinces are divided further to accommodate numbering plan needs and toll call routing ...
For this size of the network, a unique two-digit code for each numbering plan area (NPA) would have been sufficient. However, AT&T wanted to preserve existing dialing practices by only dialing the local number for local calls; it was therefore necessary to distinguish the NPA codes from central office codes automatically by the switching system.
The North American Numbering Plan (NANP) divides the territories of its members into geographic numbering plan areas (NPAs). Each NPA is identified by one or more numbering plan area codes (NPA codes, or area codes), consisting of three digits that are prefixed to each local telephone number having seven digits.
A November 1998 relief plan was approved by the CPUC that proposed an overlay complex for NPA 408, with the new area code 669. [4] However, by December 1999, the CPUC suspended the 408 overlay, along with all other then-scheduled overlay relief actions (NPAs 415, 510, 650, 714, and 909), [ 5 ] due to the implementation of telephone number ...