Nowadays, telecommunications in Indonesia have entered the convergence era, when telecommunications operators compete to develop an integated network infrastructure, in order to provide better quality of service to their customers. The convergence can reduce operational expanses, as swell as preparing the telecommunication operator to be Next Geneation NEtwork (NGN) ready PT Indosat, Tbk, as an old player in Indonesia telcommunications industry, has migrated its previous three IP /MPLS networks to a single IP/MPLS ba kbone. Migration to SIngle IP/MPLS backbone in PT Indosat was triggered by loss of network infrastructure usage, which had not been consolidated. In addition, PT Indosat Needs to gain more benefits from the usage of single network backbone. Analysis on PT Indosat migration strategies, and evaluation of the migration achievement have been done in this Final Project. Both of them have been conducted by literature studies, observation, and interviews with the stakeholder involved in migration. The lesson learnt from the migration at PT Indosat is a neccessity of longer preparation and deeper analysis to the existing network. Those processes must been accomplished before initializing the migration. It can minimize failure risks during the migration. It gives many benefits for PT Indosat and its custoers, as further discussed completely in this Final Project. Keywords: SIngle IP/MPLS Backbone; Migration