Cisco Systems The Session Initiation Protocol (SIP) has existing mechanisms for securing its signaling messages. SIP has several transport layers it works across: TCP, UDP, SCTP, and TLS over TCP. There currently is no mechanism to ensure that if TLS over TCP is chosen by the originating UAC, the messaging will remain encrypted on a hop-by-hop basis to the destination UAS. This document discusses this scenario, providing the requirements for such to exist, and offering pieces of a possible solution for this set of requirements.