[Freeswitch-users] Support for actual Silence Suppression

[Markus von Arx]

Hi

I'd like to configure FreeSWITCH in such a way that it does actual real
silence suppression and reduce the used network bandwidth during silence
periods.

By actual real silence suppression I mean that it uses one of the two
options described in RFC 3389 chapter 5, so either
1) Sending RTP packets with payload 13 that carry CNG description instead
of PCMU RTP packets during silence periods, and send those RTP payload 13
packets much less often than every 20 milliseconds, or
2) Use discontinuous RTP transmission during silence periods, or in other
words send PCMU RTP packets much less often than every 20 milliseconds.

So my questions:
1) Does FreeSWITCH support on of those two options described above?
2) If yes, how do I configure FreeSWITCH to actually do it?

Btw: I do know about
https://freeswitch.org/confluence/display/FREESWITCH/VAD+and+CNG, and I
have tried most of the things described there. What I found (by using
Wireshark) is that FreeSWITCH does indeed support VAD and CNG, but that the
FreeSWITCH does not use that information to send RTP payload 13 CNG packets
nor to do discontinuous RTP transmission, but instead the FreeSWITCH
continues to send PCMU RTP packets every 20 milliseconds and puts the CNG
audio inside these PCMU packets. This "works" in the way that the remote
party hears CNG, but this is not silence suppression as it does not reduce
the network bandwidth.

Thanks a lot,
Markus
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