Aim of this paper is presentation of operating of Multi-Service Telecommunication Systems (MSTS) [1], which have the star or multi-star structure, considering parameters, which influence on system productivity, creating of functional and mathematical models, designing of basics methodology and methods, which are necessary for quicker automated modeling, estimation and choosing parameters of MSTS on earlier stages of their creation, construction or modernization. These MSTSs are oriented on different information exchange (data, voice and video) in regional or Metropolitan Area Networks (MANs) for transmission of information between subscribers, Local and Wide Area Networks (LAN, WAN). So MSTS is the core of MAN which has big size (radius) for multi-service information exchange and where is need to consider too large loading. This paper includes the estimation methods and mathematical model of MSTS's operating, performance and efficiency. The outline method [2] is used to describe the different services and allows considering the data transmission, Internet access, telephone messages, and video/audio multicast. The mathematical modeling is applying for performance and the system's cost for accounting. The loading balancing is making by using of the ravine method [3]. Implementing this methodology any engineer can get the real system?s parameters and channel?s configurations of core MSTS, which reflect a real exchange processes.