VoIP Security — Attacks

ABSTRACT Voice over IP (VoIP) technology is being extensively andrapidly deployed. Flexibility and cost efficiency are the key factors luringenterprises to transition to VoIP. Some security problems may surface with thewidespread deployment of VoIP. This article presents an overview of VoIPsystems and its security issues. First, we briefly describe basic VoIP architectureand its fundamental differences compared to PSTN. Next, basic VoIP proto-cols used for signaling and media transport, as well as defense mechanisms aredescribed. Finally, current and potential VoIP attacks along with theapproaches that have been adopted to counter the attacks are discussed. KEYWORDS VoIP, PSTN, security, defense mechanism, attack INTRODUCTION VoIP (Voice over Internet Protocol) has fast emerged as a standard for voicecommunication using the Internet. As VoIP uses the existing IP network, itdramatically reduces cost of communication typically with traditional PSTN(Public Switched Telephone Network). In addition, ease of deployment andreduced communication hardware make VoIP a compelling solution for voicecommunication on the Internet. Further, VoIP provides a flexibility of value-added and personalized services for defining customized solutions. As a result,most of the control which existed in PSTN’s central infrastructure has beentransferred to the end devices by deploying the VoIP communication infra-structure.With the advent of VoIP technology, an increasing number of telecommu-nication service providers have stated to integrate VoIP solutions into theirsystems and provide VoIP services to their customer base. Equipment manu-facturers and end users have greatly benefited from performance advance-ments, cost reduction, and feature support provided by the VoIP technology.VoIP is a technology for transmitting voice packets on the existing IP net-work. Unlike PSTN, an IP network is packet switched. In PSTN, when a phonecall between two parties is initiated, there exists a physical circuit connectingthe two parties. After the call is established, the parties communicate and thecircuit is reserved until the parties finish the communication. In contrast, onan IP network, all communication is carried out using IP packets. When a