This research examines the readiness for Mobile Number Portability (MNP) adoption in Mongolia. MNP enables mobile users to retain their mobile telephone numbers when they changing from one mobile network operator to another one. This study is based on the modified conceptual framework of network readiness index from Global Information Technology Forum, are analyzed examples of several readiness impact adoption of MNP service. Two countries, Korea and Lithuania, were chosen their best practice for MNP adoption. Our modelled results are conducted through 3 categories: regulatory, economic and technology readiness. Also this research covers regulatory impact of MNP service where is considering probability of adoption in reality. Based on the benchmarking analysis we can offer several recommendations to the interested party. Update of legal frameworks related to MNP and set-up study group of stakeholders. Also we propose to make a feasibility study and cost-benefit analysis for whole landscape is economic component for future success for implementing that service in Mongolia. In case of high social expectations for implementing MNP service, this research is a good guideline for regulatory authority of Mongolia.