Silence Suppression Support - AudioCodes Mediant 1000 User Manual

User's Manual
Configuration is performed through the ini file (the DTMFTransportType=3 parameter), or
through the Web. This value is used by MEGACO as the default value, but commands can
override it.
To enable RFC 2833 via a command, add a payload type in the media line of the SDP and
define this payload type to be RF 2833 according to the following example:
v=0
c= IN IP4 $
m=audio $ RTP/AVP 0 97
a=rtpmap:97 telephone-event 0-15
'telephone-event' is the name defined in RFC 2833, and 97 is used as the payload number
(any number from the dynamic range can be used).
Negotiation is performed according to the following rules:
If the remote side does not specify the 'telephone-event' in the SDP, the Mediant 1000
uses the default value as the transport type.
If the local and remote payload types are different, the remote payload number is
used.
Therefore, if a user needs to activate the RFC 2833 only when both sides agree on it,
users should configure the default value to be different to RFC 2833 (e.g., Transparent).

7.2.2.11 Silence Suppression Support

Silence suppression can be enabled in two ways:
1.
Configure it to ON through one of the configuration tools. This is a static way, and
2.
applies to all calls.
Use the SDP attribute a=silencesupp:on both for the local and remote side. This is
3.
done on a per call basis.
Silence suppression can be disabled by:
4.
Setting it to OFF in the ini file. This is a static way, and applies to all calls.
5.
For G.729 or G.723 - If the remote descriptor contains the a=fmtp line with annexb=no
6.
(G.729) or annexa=no (G.723). Note that the default for the annex fields in the SDP is
Yes. Therefore, if this line is omitted, the assumption is that this side supports the
silence suppression according to the annex.
Using the SDP attribute a=silencesupp:off in the local or remote side. This is
7.
performed on a per call basis. Note that the silencesupp attribute is specified only in
RFC 3108 (SDP for ATM). However, as parsers ignore fields they do not recognize, it
is legal to use it for IP also, assuming that the call manager is capable of doing it.
In all other cases, the Mediant 1000 default value is used.
8.
The table below summarizes the operation of silence suppression:
Version 4.6 87
7. Standard Control Protocols
August 2005