User's Manual

Chapter 14: Audio codecs
The optional audio codecs feature allows you to select the audio compression or decompression algorithm
(codec) used on the IP Deskphone. You provision codecs using the Device Configuration file, and then
the user can select from the provisioned codecs using the Audio menu on the IP Deskphone. This feature
supports wideband audio performance, where wideband is defined as the frequency range between 150
and 6800 Hz.
When the user selects an audio codec, that codec is used for both incoming and outgoing calls.
The following table lists the audio codecs supported by IP Deskphone.
Table 37: Audio codecs supported by IP Deskphone
Codecs Description
G.722 This codec is a wideband audio codec.
G.723.1 This codec is a compressed, non-wideband audio codec. It provides
high-quality audio with less network connection requirements. This
codec is ideal for bandwidth-conscious environments that do not
support higher quality encoding. Expanded support of the existing
G.729a codec with Annex allows for two byte Silence Insertion
Descriptor (SID) frame for CNG.
G.711 a-law PCMA
G.711 mu-law PCMU
G.729 Expanded supported of the existing G.729a codec with AnnexB
(G.729b) allows for Comfort Noise Generation (CNG).
In the case of an upgrade from a UNIStim IP Deskphone or an earlier version of the SIP firmware, Avaya
recommends that you specify the preferred codec in the Device Configuration file; otherwise the default
value is used.
The G.711 codec (PCMU and PCMA) is always used to place the codec list for emergency 911 calls. The
G.711 codec is always used to receive incoming calls from the emergency operator. If the administrator
disables this codec, the SIP phone can make outgoing non-emergency calls.
You can configure a maximum of 15 codecs. You can enable or disable the use of specific codecs for
incoming and outgoing calls, though incoming and outgoing calls are not specifically independent.
The following table contains static payload types and other parameters for the supported codecs.
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