This paper is intended to highlight the various computational methods that are applied in fixed line telecommunication in view of their importance and underlying applications to the providers of fixed line telephone services including regional and local distance. These include companies that primarily provide telephone services through the internet. It is also intended to highlight the uses /applications of mathematical and statistical computational methods on this platform. The range of application is broad and it involves transportation network, teleprocessing network and energy transport systems involved. However, beyond apparent practical diversity of applications involved, most of these applications can be accounted for by rather a limited number of computational methods involved. One of the main purposes of this paper is to elucidate the specific computational methods applied in specific areas and how they are applied in order to make the system run appropriately and efficiently. Among these computational methods include linear interpolation, spline interpolation, Monte Carlo methods and Lagrange interpolation.