Neustar Mozilla Mozilla Vigilsec Although the Session Initital Protocol (SIP) includes a suite of security services that has been expanded by numerous specifications over the years, there is no single place that explains how to use SIP to establish confidential media sessions. Additionally, existing mechanisms have some feature gaps that need to be identified and resolved in order for them to address the pervasive monitoring threat model. This specification describes practices for negotiating confidential media with SIP, including both comprehensive security solutions which bind the media to SIP-layer identities as well as opportunistic security solutions.