In the telecommunication service provider industry that has service similarity among competitors, Customer Relationship Management (CRM) plays an important role in business operational and analytical activities to understand customer needs comprehensively so the company can provide excellence customer service. The role of CRM become more important nowadays when conventional telecommunication company should transform into digital telecommunication company. CRM development strategies need to be planned so company can take the right steps in implementing CRM. The purpose of this paper is to give understanding on establishing CRM Change Management Strategy using proposed CRM Maturity Model (CRM3) assessment based on Detecon Model and evaluated using eTOM (Enhanced Telecom Operational Map). The assessment result provides a detailed description of function maturity in accordance with the best practice of telecommunication business process framework which can be mapped into the organization level. This case study of an Indonesian Telecommunication show that the implementation of CRM has maturity level of 3.67 (Established) on a scale of 5 and give 12 recommendations.