Due to natural oligopolistic industry characteristics and huge influences on national and home economy, Telco Industry is regarded as a regulated industry. Thus, telco companies, including CATV, prepare not only management accounting reports for internal use but also regulatory accounting reports to be submitted to the regulatory agency. For telco companies, smooth integration of these financial, managerial and regulatory reporting requirements with legacies such as billing system, network operating systems is important to achieve operational efficiency and overall competency. This research studies telco ERP cost module implementation in order to provide theoretical and practical guidance for integrated information system. Especially, case analysis focuses on cost reduction and network costing implementation that involves Building Block Costing methodologies.