Abstract: Provided is an apparatus for calculating an absolute difference capable of efficiently performing an absolute difference using an adder. The apparatus for calculating an absolute difference includes a comparator comparing values of two integers, first and second selectors each selecting and outputting one of the two integers according to the comparison results of the comparator, an inverter complementing the result value selected by the second selector; and an adder adding up the result value selected by the first selector, the value complemented by the inverter, and 1.

Abstract: A method of effectively managing a database system for mobile number portability (MNP) including constructing a database associated with the MNP of a neutral organization including a first database connected to number portability management systems of a plurality of wired or wireless telecommunications service providers and a second database connected to subscriber managements systems of the wireless telecommunications service providers; transmitting data required for number portability call processing to the first database after the number portability processing for the wired telecommunications service providers has been completed by the second database; and allocating associated information to the wired or wireless telecommunications service providers requiring the number portability call processing by the first database based on the data.