Voice over IP (VoIP) service is expected to play a key role to new ways of communication. It takes advantage of Internet Protocols by using packet networks to transmit voice and multimedia data, thus providing extreme cost savings. On the other hand, this technology has inherited drawbacks, like SPAM over Internet Telephony (SPIT). A well-established method to tackle SPIT is the use of CAPTCHAs...

Increasing the popularity of SIP based services (VoIP, IPTV, IMS infrastructure) lead to concerns about its ‎security. The main signaling protocol of next generation networks and VoIP systems is Session Initiation Protocol ‎ ‎ (SIP). Inherent vulnerabilities of SIP, misconfiguration of its related components and also its implementation ‎deficiencies cause some security concerns in SIP based inf...

In the near future, the Internet is likely to become an All-IP network that provides various multimedia services over wireless networks. Although the earliest VoIP applications did not consider the end-node mobility, researchers have attempted to support mobility in current VoIP protocols, such as Session Initial Protocol (SIP)-based mobility. The SIP-based mobility is considered because it can...

In this paper we describe a new, lightweight security mechanism for PSTN-VoIP cooperation that is based on two information hiding techniques: digital watermarking and steganography. Proposed scheme is especially suitable for PSTN-IP-PSTN (toll-by-passing) scenario which nowadays is very popular application of IP Telephony systems. With the use of this mechanism we authenticate end-to-end transm...

A new, lightweight security mechanism for the PSTN-VoIP hybrid networks is described. It is based on the two informationhiding techniques: audio watermarking and network steganography. The proposed scheme is suitable especially for the PSTN-IP-PSTN (toll-by-passing) scenario, which nowadays is a very popular application of the IP Telephony systems. Proposed mechanism can be used to authenticate...

The traditional circuit-switched telecommunication network and the packet-switched data network are converging to a single packet-switched network. One important application of the converged network is telephony communications, also referred to as VoIP (Voice over IP). Call signaling protocols, such as H.323, SIP and MGCP, have been developed to support VoIP communications. To enable devices us...

Modelling and Verification of Interworking between SIP and H.323 Ligang Wang Various standards organizations have considered signaling for voice and video over IP from different approaches. There are currently two standards for signaling and control of Internet telephone calls, namely ITU-T Recommendation H.323 and the IETF Session Initiation Protocol (SIP). H.323 is an umbrella standard that p...

IP telephony is less confined than traditional PSTN telephony. As a consequence, it is more exposed to security attacks. These attacks are specific to VoIP protocols such as SPIT, or are inherited from the IP layer such as ARP poisoning. Protection mechanisms are often available, but they may seriously impact on the quality of service of such critical environments. We propose to exploit and aut...

A Document Format for Expressing Authorization Policies to tackle Spam and Unwanted Communication for Internet Telephony draft-tschofenig-sipping-spit-policy-03.txt Status of this Memo By submitting this Internet-Draft, each author represents that any applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will b...

It is the requirement of the next generation communication systems that devices should provide all existing and future communication services in integral way. A novel distributed wireless VoIP infrastructure based on SIP protocol, WiFi, and smart devices is proposed in this paper. The proposed architecture of the infrastructure is simple, manageable, stable, and extendable. The prototype test b...