04-10-2010, 09:21 AM
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Introduction
Voice over Internet Protocol (VoIP) is a method for making phone calls over the Internet or using
private networks. Traditional phone calls must travel over a series of switches and circuits owned by the
telephone companies, which control the process and the charges. By using VoIP, both businesses and
individuals can enjoy a substantial cost savings, especially while making long-distance calls.
VoIP at a technical level is a communications method that uses the competing standards Session
Initiation Protocol (SIP)1 and H.323,2 both of which are widely deployed. The two standards deal
with the routing of voice conversations over the Internet, or IP-based networks. The standards define
protocols that are derived from traditional phone systems. Signaling protocols replace the traditional
private branch exchange (PBX) functions and are carried out by server-based IP PBXs with application
software. Examples of this software include Cisco Call Manager, Nortel CallPilot, and Asterisk. The
second type, media protocols, define the protocols used between two endpoints or VoIP phone devices.
Examples include the Cisco 7900 series phones or a VoIP wireless phone. Vulnerabilities in VoIP have
been found in the signaling and media protocols, the call management software, and in the VoIP phone
devices themselves.
This report will discuss major VoIP vulnerabilities, how attacks occur, and how to protect your enterprise
from VoIP attacks.