Threats Targeting the IP Telephony System

The main threats targeting the IP telephony system are as follows:

• Loss of privacy If calls can be sniffed, conversations can be replayed or eavesdropped. Because of the open nature of IP networks and, especially, the low trust level in the Internet, privacy is a commonly raised concern when comparing IP telephony solutions against traditional telephony solutions.
• Loss of integrity If voice call signaling or media messages can be intercepted, they can be modified. Although this issue might not arise for human conversations very often, do not forget that calls such as telebanking, e-mail or voice-mail access over a telephone, and similar applications using interactive voice response (IVR) might require secure communication.
• Impersonation Identity spoofing is not limited to humans (for instance, the person behind a telephone) but can also extend to devices, such as Cisco CallManager, a voice gateway, or an IP phone.
• Denial of Service (DoS) These attacks cause loss of functionality. They can be directed against IP telephony components, such as voice gateways, Cisco CallManager nodes, or IP phones, or against the underlying infrastructure. An example is replacing IP phone configuration files or images stored on a TFTP server with invalid files that cause the IP phone to malfunction.