RingRTC is the calling library used by Signal to manage voice and video sessions. It handles parts of the real-time communication process, including call signaling and media, connecting app controls such as mute or hang-up with the underlying audio and video streams.
Its security matters because a flaw in call-state or teardown logic could cause the app’s displayed state to differ from what the media system is doing-for example, if a stream does not stop promptly after a call ends. That would be a session-handling problem, not necessarily a failure of end-to-end encryption. Defenders should keep Signal clients and their bundled components updated through official channels; users can verify that device audio or video has stopped if a call behaves unexpectedly.