Signalling and Media Flows
TLS – Signalling Encryption
Establishing, controlling and terminating internet calls according to the SIP specification can be encrypted, and therefore secured, via TLS. TLS stands for Transport Layer Security and is a protocol which is in turn based on SSL (Secure Socket Layer) version 3.0. It implements a secure – in other words authentic and confidential – channel on the transport layer. The signalling data is transmitted together with an SRTP key for the encrypted voice data.
SRTP – Media Encryption
The SRTP protocol, designed for real-time communication, stands for security of voice data transmissions. By encrypting the data with symmetrical encryption to AES (Advanced Encryption Standard), eavesdropping is effectively prevented.