This paper presents a method for modeling and evaluating the performances of telecommunication software maintenance process. The method can be used as a special technique within the given generic model as part of an organizational effort to upgrade process maturity and efficiency. It is based on the modeling of software maintenance process as queuing networks and applies process simulation to determine its performances. The method allows efficient comparison of the alternative process designs without the risks associated with the experiments in real life. Its activities can be implemented in various telecommunication software maintenance processes and other software processes to be formally presented and analyzed for improvement purposes. Implementation is presented in a case study with software maintenance process in a telecommunications company. The results show practicability and applicability of the method in the software organization with the aim of improving software maintenance process.