NGN
NGN Softswitch Based Architectures

NGN architecture based on software switching technology (softswitch) can be supposed as first and unique evolution step in NGN, although there are more modern architecture available nowadays (for example see chapter IMS based architecture). However, it has built up philosophy of building of new NGN networks and validated principles and features of NGN architecture and its components towards its next evolution [3]. This architecture was the first which drive was significantly motivated by telecommunication vendors, naturally reflecting on massive development of VoIP protocol family and by telecommunication providers demand to implement services more modern and more efficient way. Due to this fact it is not strictly standardized and we can see there several different attitudes of telecommunication vendors how to provide some features, how to distribute components across network including distribution of functional entities inside control element plane. Knowledge of this architectural approach is important for understanding of next evolved architectures and principles. Components of softswitch based architecture you can see in next Figure.

Components of softswitch based architecture

Media Gateway Controller/call agent/softswitch: generally serves as components for controlling of communication relations of users and other network components; provides call routing, network signaling, billing, and other logical functions.

Media Gateway: operate within transport plane, perform all function related to media physical transport between different networks, media processing functions (transcoding, echo cancellation, jitter managing), tones processing and management of information transport

Application Server: it is obviously implemented to perform functionalities specific to certain service, perform specialized service logic call control, also includes more functionalities in terms of user web interface, end-points management, etc. For example it can provide specific videoconferencing service, Call Centre service or IP Centrex service.

Media Server: provides functionalities allow interaction between calling party and application using end-point device. It provides Media Resource Functions (tones detection, speech synthesis and recognition, compressions, media mixing, etc.) and Media Control Functions – control of media functions (voice message play management, conference bridge, fax messages management, etc.).