A Distributed IP Multimedia Subsystem (IMS)

This document presents the architecture of a distributed IP Multimedia Subsystem (IMS). The architecture distributes network functional elements in Distributed Hash Tables (DHT) overlay network. This work focuses on distributing the SIP proxies, such as the Serving-Call/Session Control Function (S-CSCF) and the Interrogating-Call/Session Control Function, as well as the Home Subscriber server (HSS), and up to some degree, presence servers. A combined DHT overlay network is also proposed. Distribution of the network functional elements in a DHT fashion leads to increased robustness of IMS network elements. Besides the self-organizing overlay network offers a significant savings in OPEX.