High Quality Content by WIKIPEDIA articles! In telephony, especially in North America, an overlay plan is the practice of introducing a new area code by applying it onto a geographic area that is already occupied by one or more existing area codes, resulting in two (or more) area codes serving the same area. Prior to the introduction of overlay plans, the method of introducing new area codes (also known as numbering plan areas or NPAs) in a region was to divide the existing territory of one area code into two (or more) pieces, allowing the more established or developed section to retain the original area code, and changing the numbering space of the other section(s) to have a new area code.

Данное издание не является оригинальным. Книга печатается по технологии принт-он-деманд после получения заказа.