Softswitch is an innovative concept in the field of telecommunication and ICT, which creates new challenges and opportunities for the network operators, service providers and researchers. The migration from PSTN to NGN involves the convergence between PSTN and IP network that is a single network for voice, data and video. Softswitch performs all analysis functions, routes signalling messages and handles traffic data. So it requires an extension of existing charging collection mechanisms and billing system that is functionally intelligent and flexible, and provides fair policy towards end...