![]() The author of this paper discharge all responsibilities for an inappropriate use of the information here reported and suggests to try these attack techniques only in controlled environments, like test plants, and with previous authorization of the owner. The results of this article could be used by system administrators, network engineers and penetration tester in order to examine their VoIP systems. In this way the VoIP current situation will be analyzed from attacker’s point of view to discover the most vulnerable parts of the system. ![]() For each threats an example of attack is reported and explained since, in author’s opinion, the knowledge of the tools that could be used by attackers is important. This article analyzes the most common VoIP threats in order to identify existing weaknesses and suggests available countermeasures. ![]() VoIP services are often taken in use but their security threats are analyzed only under specific aspects or not taken in consideration at all. Using VoIP Media Gateway, a VoIP phone can call a legacy phone on the PSTN and vice versa with no problems since Media Gateway translates the IP packets into TDM. Software Phones (also said Softphones), IP Phones and Analog phones (which must use VoIP adapter) can connect to a PBX, where internal telephone are connected to public lines or other VoIP systems on the Internet. VoIP has seen rapid implementation over the past few years, many users choose VoIP and leave behind the traditional telephonic providers in order to pay cheaper bills for companies using VoIP is an easy way for communication between their several branches and for their teleworking employees.Īn example of a simple VoIP network can be seen in Figure 1 where VoIP works as a private telephone network and it is transparent to the PSTN. VoIP usually refers to communications multimedia applications which are transported via Packet-Switched Network (such as Internet) instead of the PSTN. Voice over Internet Protocol (VoIP) is a newer technology that allows phone conversations to be transferred over the computer networks, it transforms analog and digital audio signals in data packets. TDM transmits and receives independent signals over a common signal path by means of synchronized switches at each end of the transmission line, so that each signal appears on the line only a fraction of a time in an alternating pattern. When PSTN became digital, a method called Time Division Multiplexed (TDM) was created. When telephone business grew, Private Branch eXchanges (PBX) were designed, and deployed in office settings to provide the increasing of telephone lines and to connect internal callers (over trunk lines) through either the PSTN or eventually to destination callers. Initially, the PSTN was a simple one-to-one telephone line connecting phones from one room to another. ![]() Initially, the most basic analog network service, called POTS (Plain Old Telephone Service), used a pair of twisted copper wires in order to connect a residential phone to a central office from where a residential customer can dial out in the PSTN. The Public Switched Telephone Network (PSTN) is a global system of interconnected, various analog sized phone networks which provides users the capability to carry voice conversations with each other.
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