The call-attempt behavior in a telecommunications service is influenced by the launch of new services and the choice of subscribers. On Feb 28, 2005, there was a disastrous shut-down of major local electronic switching systems (ESS) due to an abrupt increase of call-attempts. This incident turned out to be a strong proof that appropriate forecasting attempts are necessary not only for the capacity planning of network but also for the quality control of ESS. In this paper, forecasting models are first developed to estimate the daily ESS call-attempts and user retrial rates and then meaningful interpretations of results will follow. Finally future research topics will be presented.