Jingle supports notifying your peer that you've muted a stream, or the entire call. We don't have a way to represent this in Telepathy yet.
We can't just add a Muted flag to CallStates, because you can mute individual streams.
Here's the Mute interface that Maemo 5 uses in GSM calls:
Maemo 5's interface just has a single boolean, "am I muting the call?". However, Sjoerd suggests that what we actually want (particularly for Muji) is a mute flag per content (so in practice, audio and video, where "muting video" means sending no frames, or sending black frames, or something).
We briefly discussed the possibility of protocols existing where you could stop sending your audio to particular people, e.g. if I'm in a call with Sjoerd and Will, I could stop sending audio to Will but continue talking to Sjoerd.
However, the only use-case we could see for this is complaining about Will behind his back; as well as being somewhat antisocial, this wouldn't actually work very well, because Sjoerd will still be sending audio to Will, and if Sjoerd's microphone picks up his speakers a little bit (in practice, it will), Will can still hear what I'm saying about him. Also, making a user interface for muting streams to individual contacts doesn't sound very plausible.
There doesn't seem to be much point in adding this to StreamedMedia when Sjoerd's Call API (Bug #24936) is just round the corner, so we'll fix this in the Call channel type.
*** This bug has been marked as a duplicate of bug 26807 ***