Network planning of third generation (3G) and fourth generation (4G) mobile systems for enabling NGN services is a very complex process with many different aspects, the result of which influences on the success of network operators. The first part of the monograph deals with 3G IMS-capable Core Network dimensioning aspects such as multiservice traffic load estimation, performance evaluation of IMS nodes, etc. The second part of the monograph is focused on 4G Radio Access Network (RAN) topological design aspects to minimize expenses with the RAN deployment taking into account reliability requirements. The methodologies presented in the monograph enable establishing requirements, such as throughput of channels, performance of nodes and routers, both to the equipment of internal IP-networks in the 3G/4G mobile systems and to the gateways providing the interaction between the 3G/4G systems and external networks. Results of the research allow making easier both the preparation of business-plans for development of wide range of NGN services and the preparation of system projects for deployment of 3G/4G mobile network equipment.