Phone Authentication and Encryption

Although mechanisms such as DHCP snooping can help prevent certain types of DoS attacks, IP telephony systems are also vulnerable to other types of attack, such as interception and eavesdropping, as well as malicious insertion of packets into a voice signaling or media stream. Therefore, it is important to secure IP telephony networks, and Cisco CUCM and other devices can be configured to use encryption and authentication to protect against attacks.

Cisco CUCM, Cisco IP phones, and voice gateways can be configured to authenticate and encrypt voice signaling and media traffic, and Cisco IP phones can be configured to authenticate phone images and configuration files. These functions rely on a public key infrastructure (PKI) and the issuance of certificates.