IMS Based IP Telephony Over MPLS Network

Due to the fast growth of the internet, the present trend people request more applications over internet such as video calling and flash. VoIP (Voice over Internet Protocol) is an emerging technology for voice communication which deploys many techniques to produce a high-quality service. Signaling is one of the most prominent key of Voice over IP; the second one is most promised approaches in this case are SIP and IMS. This paper will compare the call setup delay of SIP and IMS, Measure the QoS of a Network and compare Different voice codec’s using different parameters using a powerful network simulation tool (OPNET Modeler) which enables network simulation by employing various protocols

Delivering Live Multimedia Streams to Mobile Hosts in a Wireless Internet with Multiple Content Aggregators

We consider the distribution of channels of live multimedia content (e.g., radio or TV broadcasts) via multiple content aggregators. In our work, an aggregator receives channels from content sources and redistributes them to a potentially large number of mobile hosts. Each aggregator can offer a channel in various configurations to cater for different wireless links, mobile hosts, and user preferences. As a result, a mobile host can generally choose from different configurations of the same channel offered by multiple alternative aggregators, which may be available through different interfaces (e.g., in a hotspot). A mobile host may need to handoff to another aggregator once it receives a channel. To prevent service disruption, a mobile host may for instance need to handoff to another aggregator when it leaves the subnets that make up its current aggregator�s service area (e.g., a hotspot or a cellular network).\ud In this paper, we present the design of a system that enables (multi-homed) mobile hosts to seamlessly handoff from one aggregator to another so that they can continue to receive a channel wherever they go. We concentrate on handoffs between aggregators as a result of a mobile host crossing a subnet boundary. As part of the system, we discuss a lightweight application-level protocol that enables mobile hosts to select the aggregator that provides the �best� configuration of a channel. The protocol comes into play when a mobile host begins to receive a channel and when it crosses a subnet boundary while receiving the channel. We show how our protocol can be implemented using the standard IETF session control and description protocols SIP and SDP. The implementation combines SIP and SDP�s offer-answer model in a novel way

SIP based IP-telephony network security analysis

Masteroppgave i informasjons- og kommunikasjonsteknologi 2004 - Høgskolen i Agder, GrimstadThis thesis evaluates the SIP Protocol implementation used in the Voice over IP (VoIP) solution at the fibre/DSL network of Èlla Kommunikasjon AS. The evaluation focuses on security in the telephony service, and is performed from the perspective of an attacker trying to find weaknesses in the network. For each type of attempt by the malicious attacker, we examined the security level and possible solutions to flaws in the system. The conclusion of this analysis is that the VoIP service is exploitable, and that serious improvements are needed to achieve a satisfying level of security for the system