Audio Features
166
Codec
Algorithm
Reference
Bit Rate
Sample Rate
Packetization Time
iLBC_15_2kbps
iLBC
RFC 3952
15.2 Kbps
8 Ksps
20ms
iLBC_13_33kbps
iLBC
RFC 3952
13.33 Kbps
8 Ksps
30ms
opus
opus
RFC 6716
8-12 Kbps
16-20 Kbps
28-40 Kbps
48-64 Kbps
64-128 Kbps
8 Ksps
12 Ksps
16 Ksps
24 Ksps
48 Ksps
20ms
Note
: The network bandwidth necessary to send the encoded audio is typically 5~10% higher than the bit rate due to pack-
etization overhead. For example, a two-way G.722 audio call at 64 Kbps consumes about 135 Kbps of network bandwidth.
The Opus codec supports various audio bandwidths, defined as follows:
Abbreviation
Audio Bandwidth
Sample Rate (Effective)
NB (narrowband)
4 kHz
8 kHz
MB (medium-band)
6 kHz
12 kHz
WB (wideband)
8 kHz
16 kHz
SWB (super-wideband)
12 kHz
24 kHz
FB (fullband)
20 kHz
48 kHz
Note
: The T40P/T40G/T23P/T23G/T21(P) E2/T19(P) E2 phones support using WB for Opus encoding, and using NB, MB,
WB, SWB and FB for Opus decoding.
The T57W/T54W/T53W/T53/T48U/T48S/T46U/T46S/T43U/T42U/T42S/T41S/T27G phones support using WB
(default) or NB for Opus encoding, and using NB, MB, WB, SWB and FB for Opus decoding.
The CP920 phones support using anyone from NB to WB for opus encoding, and using NB, MB, WB, SWB and FB
for opus decoding.
The phones support up to two calls or a three-way conference when using Opus.
The following table lists the audio codecs supported by each phone model:
Phone Model
Supported Audio Codecs
Default Audio
Codecs
T48G/T46G/T42G/T41P/T29G
G722, PCMA, PCMU, G729, G726-16,
G726-24, G726-32, G726-40, G723_53,
G723_63, iLBC_15_2kpbs, iLBC_13_
33kpbs
G722, PCMA, PCMU,
G729
T57W/T54W/T53W/T53/T48U/T48S/T46U/T46S/
T43U/T42S/T42U/T41S/T27G
G722, PCMA, PCMU, G729, G726-16,
G726-24, G726-32, G726-40, G723_53,
G723_63, opus, iLBC_15_2kpbs, iLBC_
13_33kpbs
G722, PCMA, PCMU,
G729
T40P/T40G/T23P/T23G/T21(P) E2/
T19(P) E2
G722, PCMA, PCMU, G729, G726-16,
G726-24, G726-32, G726-40, opus, iLBC_
15_2kpbs, iLBC_13_33kpbs
G722, PCMA, PCMU,
G729
