In emerging markets, the proliferation of mobile telecommunications services has been accompanied by a surge in SIM card-related fraud, posing significant risks to consumers, businesses, and national security. SIM card fraud—including SIM swap, identity cloning, and unauthorized number porting—has evolved into a sophisticated threat exploiting regulatory gaps, weak authentication protocols, and fragmented identity systems. These vulnerabilities are exacerbated in regions with underdeveloped customer verification infrastructure and limited integration between mobile network operators (MNOs) and national identity databases. This paper proposes a comprehensive security framework for implementing Customer-Identity Management (CIM) systems as a frontline strategy to mitigate SIM card fraud in emerging-market telcos. Beginning with a broader analysis of the fraud landscape, the study identifies the economic, operational, and reputational impact of SIM fraud on MNOs and consumers. It then evaluates existing countermeasures and reveals their shortcomings, particularly in relation to user authentication, real-time identity validation, and post-issuance monitoring. The proposed framework integrates biometric-enabled Know Your Customer (KYC) systems, federated identity management, real-time analytics, and cross-industry collaboration. Emphasis is placed on data interoperability, regulatory alignment, and risk-based authentication to ensure robust, scalable, and context-sensitive deployments. Pilot case studies from Sub-Saharan Africa and Southeast Asia illustrate the practical benefits of implementing CIM, including reduced fraud rates, improved customer trust, and regulatory compliance. The paper concludes with policy recommendations and implementation guidelines for telcos, regulators, and technology providers to cooperatively advance secure and user-centric identity infrastructures. By aligning technical innovations with governance models, emerging-market telcos can move from reactive fraud control to proactive identity assurance.