Appearance
Calls
Voice and video calls start from a chat or the Calls filter.
During a call
Mute, camera on/off, flip camera, speaker, and end. Some devices can share a screen; if someone is already sharing, wait.
TwinCam (second camera) on a call needs hardware that actually has two usable cameras.
Encryption
When the padlock / “E2E media on” state is shown, call media is encrypted between the devices on that call. If the device cannot negotiate E2E, the call may still connect with E2E unavailable — the UI says so. Do not assume a call is private if the UI says it is not.