The World Telecommunication Standardization Assembly (Johannesburg, 2008), considering the crucial importance of the information and communication technologies (ICT) infrastructure to practically all forms of social and economic activity; that the legacy public switched telephone network (PSTN) has a level of inherentsecurity properties because of its hierarchical structure and built-in management systems; that IP networks provide reduced separation between user components and network components if adequate care is not taken in the security design and management.