Problems with securing IP Telephony systems, insufficient standardization and lack of security mechanisms emerged the need for new approaches and solutions. In this paper a new, alternative security architecture for voice-systems is presented. It is based on digital watermarking: a new, flexible and powerful technology that is increasingly gaining more and more attention. Besides known applicat...

Asterisk is a leading open source telephony software/system, easily implemented over intranet and internet. Asterisk empowers developers and integrators to create advanced communication solutions. An Asterisk system is a low cost type of a traditional PBX system. Any phone controlled by an Asterisk system can call a VoIP or analog phone controlled or managed by a traditional telephone system or...

To realize wireless Internet Telephony and Streaming Multimedia in a highly mobile environment while providing proper quality of service, an experimental testbed emulating a wireless internet has been built. Different functionalities such as signaling, registration, configuration, dynamic binding, location management, flexible streaming application have been designed, prototyped and experimente...

A revolution is taking place in telecommunication networks. New services are appearing on platforms such as third generation cellular phones (3G) and broadband Internet access. This motivates the transition from mostly switched to all-IP networks. The replacement of the traditional shallow and well-defined interface to telephony networks brings accrued flexibility, but also makes the network ac...

The next generation communication system will provide high quality multimedia service in a more flexible and intelligent manner. In this paper, we propose a new SIP over MPLS network architecture to achieve this goal. To integrate SIP protocol with the traffic engineering function of MPLS network seamlessly and facilitate SIP call setup, the SIP-MPLS traffic aggregation server (TA server) is hi...

This paper examines speech quality and Internet protocol (IP) telephony. Voice over IP requires specific treatment of the signals transmitted in order to avoid the problems reported by a study conducted by KPN Netherlands and reported at the ETSI-STQ workshop "Quality issues for IPtelephony" June 1999: A pilot study was organized in 1998/1999. The requirement was that the network quality should...

This paper presents a non-intrusive method of determining network performance parameters for voice packet flows within a VoIP (Voice over IP, or Internet Telephony) call. An advantage of the method is that it allows not only end-to-end performance monitoring of flows, but also makes it possible to inspect the transport parameters a specific network or link when delay sensitive traffic transits ...

Purpose of this paper is to describe the theoretical basis, design and implementation of a communication system based on an adaptive voice coder tuned for IP real-time voice communications. The developed voice coder makes use of an adaptive algorithm which performs an automatic coding switch, according to the evolving congestion conditions of the underlying IP network, in order to render the co...

In interactive voice applications, FEC schemes are necessary for the recovery from packet losses. These schemes need to be simple with a light coding and decoding overhead in order to not impact the interactivity. The objective of this paper is to study a well known simple FEC scheme that has been proposed and implemented [1], [2], in which for every packet , some redundant information is added...