As the market for cellular telephones and other mobile devices, keeps growing, the demand for new services arises to attract the end users. One topic that is being discussed throughout the world today is location based services. How can a mobile station be located? And in which way this information is utilized to provide service to end user. This paper presents the design of cellular positioning system. Positioning accuracy is one of the most important performance measures. Currently, position of mobile station is calculated in terms of coordinates of base station. In this paper, signals already present in the network is used to find position of mobile station this is called as network based positioning.