VoIP Phone User
’
s Manual
9.4 CODECS Setting
If the device is running one of the four VoIP applications, this page is available for
configuring the audio CODEC parameters, as well as the Jitter Buffer settings for the
CODEC decoders.
Enter which CODECs are to be supported.
Select which complex codec is to be supported. Due to memory limitations, it is not
possible to select G723 and G729 complex codec at the same time.
Select the packetization period to be used for each selected CODEC. For MGCP, a
range of packetizations may be provided for each CODEC (to be advertised in the
device's "capabilities" set).
Select whether Silence Suppression is to be supported for each CODEC.
The Jitter Buffer settings apply to all active CODEC decoders. You may choose
between an adaptive jitter buffer and a fixed jitter buffer. For an adaptive jitter buffer,
choose the maximum allowable playout delay (in milliseconds). For a fixed jitter buffer,
choose the fixed playout delay (in milliseconds).
Finally, select whether or not a decoder should automatically switch from an
adaptive jitter buffer to a fixed jitter buffer upon fax/modem tone detection. Adaptive jitter
buffers are sometimes detrimental to fax transmission over G711 CODECs if they have to
adapt too rapidly or too extensively due to inconsistent and widespread packet delays. In
these adverse network conditions, a fixed jitter buffer provides superior performance when
handling incoming fax transmissions over G711 CODECs.
