[pt] O presente trabalho tem como meta analisar os aspectos de planejamento de redes celulares UMTS coexistentes com redes GSM, abordando de forma sintetizada os principais pontos de interesse para as operadoras de telefonia celular móvel que eventualmente estejam considerando a possibilidade de coexistência entre esses sistemas. São abordados de forma especial os processos de interoperabilidade entre as redes UMTS e GSM/GPRS/EDGE. / [en] This work has as its purpose to analyze and present on a concise manner the planning aspects for new UMTS networks as well as its interoperability issues concerning GSM legacy layer, serving as reference for the wireless network providers which adopt UMTS over GSM/GPRS/EDGE as their short-term option for deploying existing networks. It will be given special attention to most of interoperability issues which are defined by the standardization bodies (mainly INTER-RAT) and others which are being offered by some of the most representative equipments providers.