Today's competitive enviroment, together with huge developement of IP networks used for delivering high-bandwidth services, forced telecom operators to simplify network topology, reduce operating costs, and have secure, high quality convergent network which can be easily managed and adopted according to future requirements. As a logical step with IP network developement was introduction of Voice ... [Show full abstract] over IP. For green-field operators it was an easy way to get in the business quickly with deployment of IMS based network, but for old telecom operators migration started with adaptation of old TDM based network used for old customers to new, IP network, together with deployment of IMS network. One important, and we could almost say critical element of every VoIP network is Session Border Controler (SBC). In this article we will give a brief overview of major SBC functionalities and the way of implementation in next-generation networks (NGN).