This thesis describes the modelling and simulation of a telecommunication system based on Advanced Intelligent Network (AIN) architecture for provision of telecom services. It also presents an analysis of the performance of the Service Control Point under overload conditions with the implementation of Automatic Code Gap (ACG) controls. A telecommunications system was developed to demonstrate the operation of an intelligent network Further, a set of services including Call Forward, Call Back, Call Transfer and Automatic Call Distribution were implemented on the network. This was done to exhibit the relative ease with which new services can be developed and implemented on the AIN network in a system independent manner. Further, to evaluate the performance of the Service Control Point (SCP) under overload conditions an another system was developed. The functionality for implementing ACG controls on the system was also realised. In addition, an algorithm for selection of controls was developed. An extensive set of simulations were performed on the system to determine the effectiveness of the controls in preventing overloading at the SCP. A considerable improvement in SCP performance was observed with the deployment of ACG controls OPNET, a network simulation tool, was used for developing the system.