a note for linphone users who want to use the freeswitch server

Christopher Brannon chris at the-brannons.com
Mon Feb 7 22:15:42 EST 2011

William Hubbs <w.d.hubbs at gmail.com> writes:

> There used to be music that played when you entered the conference and
> were the only one there; that may be a good reason to think about
> bringing it back some how.

If there's nobody there, I would personally rather hear silence, so that
I can play a stream of my choosing.  Plus, playing music wastes
Note that the problem also occurs if the other participants mute their
outbound audio.  I.E., no audio is being sent by the server.
The best solution is a keep-alive message of some sort.  I.E., every X
number of seconds, the freeswitch conference module sends a packet to
every connected user, saying "Hey, I'm alive".  SIP doesn't have a
keep-alive feature.  linphone automatically disconnects when X seconds
have elapsed since the last RTP packet.  The default value of X is 30.
RTP is the protocol which actually carries the audio (or video) data.
So here's the question.
Would it be possible to send an RTP packet consisting of nothing but
silence to every participant at a given interval?  This wouldn't require
much bandwidth, and it would give us the equivalent of keep-alive.

-- Chris

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