[SIPForum-discussion] Issue with Silence Suppression

[Nitin Kapoor]

Ashoke,

Basically endpoints sending audio as an RTP stream are not required to send
packets during silent periods.  The capability to stop sending RTP packets
during silent periods is known as "Silence Suppression" or VAD (Voice
Activity Detection). Whether to use Silence Suppression is usually a
configuration option on endpoints.

Here the two RFC which i know has say about Silence Suppression: 3103 &
3389( May be there is some others also which may have better details from
the above one).

Thanks,
Nitin Kapoor



RFC 3108 talks about silence suppression attribute for voice activity
detection

2010/1/15 Ashoke Kumar Ghosh <ashoke.k.ghosh at gmail.com>

>  I have some problem with Silence Suppression on from Application Server.
>
>
>
> The Appl Server works as B2BUA. It first establishes a session with media
> server after receiving an INVITE message from Softswitch for playing
> announcement & taking digits from user.
>
>
>
> Thereafter, it puts the A party on hold using Re-INVITE (The IP address for
> RTP is given as 0.0.0.0) and initiates another session with B party.
>
>
>
> Once 180 Ringing/183 Session Progress is received with B party SDP, Appl
> Server sends the A party resume using Re-INVITE and B party SDP with Silence
> Suppression on.
>
>
>
> This call flow is working for more than 3 yrs now. I have seen some old
> traces & found the same thing. But now we are getting complaints from
> carriers who claim that this is causing problem at their end.
>
>
>
> My queries
>
>
>
> 1.       What is the purpose of Silence Suppression & when it should be
> used.
>
> 2.       Which is the RFC I can refer to know more on Silence Suppression.
>
> 3.       Can Silence Suppression create a problem for proxies as claimed
> by the carrier If yes what can be problem
>
>
>
> Hope to get a quick response from experts.
>
>
>
> Regards…
>
>
>
> Ashoke Ghosh
>
>
>
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