IP networks have been becoming more popular communication infrastructures due to the lower operational costs in recent years. Mainly, usage of IP networks in voice services, which is denominated by VoIP (Voice over IP), has made difference in telephony networks not only the way of the people’s communications, but also telecommunication companies’ and operators’ solutions. In this scope, IMS (IP...

Billing is fundamental to any commercial VoIP services and it has direct impact on each individual VoIP subscriber. One of the most basic requirements of any VoIP billing function is that it must be reliable and trustworthy. From the VoIP subscriber’s perspective, VoIP billing should only charge them for the calls they have really made and for the duration they have called. Existing VoIP billin...

With the appearance of multimedia applications and the upcoming age of Voice over IP (VoIP), Voice setup and resources control protocols such as SIP and H.323 over the Internet are becoming increasingly attractive applications. In the last few years as a real competitor in traditional telephony services (PSTN), SIP has gained much attention when compared with H.323. SIP works at presentation an...

This paper reviews the IETF proposed enhancements to the Session Initialisation Protocol (SIP) to prevent the abuse of its implementation in Voice-over-IP (VoIP) communication services. We look at some of the benefits and drawbacks of these proposed enhancements to ensure trustworthy SIP message exchange. Many proxies assist in establishing of a SIP session. These proxies may modify the travers...

SPAM, defined as sending unsolicited messages to someone in bulk, might be a problem on SIP open-wide deployed networks. The responsibility for filtering or blocking calls can belong to different elements in the call flow and may depend on various factors. This document defines an authorization based policy language that allows end users to upload anti-SPIT policies to intermediaries, such as S...

The VoIP(Voice over IP) has been worldwide used and already put to practical use in many fields. However, it is needed to ensure secret of VoIP call in a special situation. It is relatively difficult to eaves-drop the commonly used PSTN in that it is connected with 1:1 circuit. However, it is difficult to ensure the secret of call on Internet because many users can connect to the Internet at th...

This thesis presents a concept to achieve non-repudiation for natural language conversations by electronically signing continuous, packet-based, digital voice communication (VoIP). Signing a VoIP-based conversation means to protect the integrity and authenticity of the bidirectional data stream and its temporal sequence which together establish the security context of the communication. The sol...

Voice over IP (VoIP) systems are gaining in popularity as the technology for transmitting voice traffic over IP networks. As the popularity of VoIP systems increases, they are being subjected to different kinds of intrusions some of which are specific to such systems and some which follow a general pattern of IP attacks. VoIP systems pose several new challenges to Intrusion Detection System (ID...

Voice over Internet Protocol (VoIP) is subject to many security threats unique to both telephony and traditional Internet data transmission. As adoption of Session Initiation Protocol (SIP)-based telephony increases, concerns are rising over risks to system confidentiality, integrity and availability. Currently, several VoIP security tools are available to detect vulnerabilities and protect aga...