Aastra Telecom 9480i Series User Manual

4-96

41-001160-03, Rev 00, Releaes 2.4  

IP Phone Administrator Guide

Silsupp is used to enable or disable silence suppression. Voice Activity Detection 
(VAD) on the IP phones is used to determine whether each individual packet 
contains useful speech data. Enabling silsupp results in decreased network 
bandwidth, by avoiding sending RTP packets for any frame where no voice 
energy was detected by the VAD.

You must enter the values for this feature in list form as shown in the following 
example:

payload=8;ptime=10;silsupp=on,payload=0;ptime=10;silsupp=off

The valid values for creating a Codec preference list are as follows.

You can specify a customized Codec preference list on a global-basis using the 
configuration files or the Aastra Web UI.

The IP phones support out-of-band Dual-Tone Multifrequency (DTMF) mode 
according to RFC2833. In the Aastra Web UI, you can enable or disable this 
feature as required. The "out-of-band DTMF" is enabled by default.

In out-of-band mode, the DTMF audio is automatically clamped (muted) and 
DTMF digits are not sent in the RTP packets.

You can configure out-of-band DTMF on a global-basis using the configuration 
files or the Aastra Web UI.

payload

0 for G.711 u-Law
8 for G.711 a-Law
18 for G.729a

ptime (in milliseconds)

5, 10, 15, 20.......90

silsupp

on

off

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