[SIPForum-discussion] Issue with Silence Suppression

Ashoke Kumar Ghosh ashoke.k.ghosh at gmail.com
Sun Jan 17 04:30:19 UTC 2010

Can you specify which rfc I can refer


From: Garrity, John N. (Infrastructure Solutions Dept.)
[mailto:john.garrity at thehartford.com] 
Sent: Saturday, January 16, 2010 1:34 AM
To: ashoke.k.ghosh at gmail.com; discussion at sipforum.org
Subject: RE: [SIPForum-discussion] Issue with Silence Suppression


You are using G.729b, providing silence suppression, and some of the
carriers only offer G.729a.  Question you carriers as to their ability to
process G.729b?


John G.



From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Ashoke Kumar Ghosh
Sent: Friday, January 15, 2010 10:09 AM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] Issue with Silence Suppression

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 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

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.




Ashoke Ghosh


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