Specifications

Configuring Audio Features
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2. Select the desired value from the pull-down list of Dual-Headset.
3. Click Confirm to accept the change.
Audio Codecs
CODEC is an abbreviation of COmpress-DECompress, capable of coding or decoding
a digital data stream or signal by implementing an algorithm. The object of the
algorithm is to represent the high-fidelity audio signal with minimum number of bits while
retaining the quality. This can effectively reduce the frame size and the bandwidth
required for audio transmission.
The default codecs used on IP phones are summarized in the following table:
Codec
Algorithm
Bit Rate
Sample Rate
Packetization Time
PCMA
G.711 a-law
64 Kbps
8 Ksps
20ms
PCMU
G.711 u-law
64 Kbps
8 Ksps
20ms
G729
G.729
8 Kbps
8 Ksps
20ms
G722
G.722
64 Kbps
16 Ksps
20ms
In addition to the codecs introduced above, IP phones also support codecs: G723_53,
G723_63, G726_16, G726_24, G726_32, G726_40 and iLBC. Codecs are configurable on
a per-line basis, instead of using defaults. You can also configure the priorities for these
desired codecs. The attribute “rtpmap” is used to define a mapping from RTP payload
codes to a codec, clock rate and other encoding parameters.