Transport Layer Security, or TLS, is a widely adopted security protocol designed to facilitate privacy and data security for communications over the Internet. A primary use case of TLS is encrypting VoIP, or voice over IP, calling. Often TLS is used alongside Secure Real-time Transport Protocol (SRTP). TLS encrypts the signaling of the calls, which you can think of as the set up and tear down portion of a call, and SRTP secures the actual media – the little ‘packets’ of data that run over the highway set up by the signaling.
Members of Cisco and Ericsson developed SRTP and was first published by the IETF in March 2004. This initial publication listed the goals and features of SRTP as both the confidentiality of RTP and RTCP payloads. The goal was to create an upgradeable framework with low bandwidth and computational cost, a small code footprint, and independence from underlying transport, network, and physical layers used by RTP.
TLS dates back to August 1986 when government agencies including the NSA teamed with several communications and computer corporations under the guise of a project called the Secure Data Network System (SDNS).
TLS/SRTP is an optional capability provided by Bandwidth, and is used to encrypt calls between the customers network and Bandwidth. Calls from Bandwidth to and from the PSTN are not encrypted.
