Ericsson Ericsson Ericsson RTP has always been a protocol that supports multiple participants each sending their own media streams in an RTP session. Unfortunately, many implementations are designed only for point to point voice over IP with a single source in each end-point. Even client implementations aimed at video conferences have often been built with the assumption around central mixers that only deliver a single media stream per media type. Thus any application that wants to allow for more advanced usage, where multiple media streams are sent and received by an end-point, has an issue with legacy implementations. This document describes the problem and proposes a signalling solution for how to use multiple SSRCs within one RTP session and at the same time handle the legacy issues.