What codec should I use for voice calls?

What codec should I use for voice calls?

TopView voice calls over VOIP allow the specification of a codec used for encoding the audio to be used during the call. This article explains what codecs are and why you might want to use a codec that is different from the defaults used by TopView.

What is a “codec”?

From Wikipedia’s definition of Audio Codec:

An audio codec is a codec (a device or computer program capable of encoding or decoding a digital data stream) that encodes or decodes audio

Why is this a VOIP configuration option?

By default, multiple codecs are offered to the VOIP server, in order of preference, and the server will negotiate the best codec with the client. 
Sometimes, the codec picked by the negotiation process may not be the best for the network or recipient devices. In these situations, you can configure TopView to specify another codec.

TopView suggests a high quality audio codec, G.722, which provides excellent calls.
If you want to test alternate codecs, we recommend starting with PCMU, PCMA, and G.729.

The codecs that will work best depend on many factors, so your experience may vary from ours. Please try many different codecs if you decide to specify custom codecs.
TopView does not provide multiple codecs as an option, choose only one custom codec for use.

TopView supports the following codecs:
Name
Alt. name
Payload type
No. of channels
Rate (Hz)
Ratet (Hz)
PCMU (G.711)
PCMU
0
1
ITU-T G.711 PCM µ-Law audio 64 kbit/s
8000
PCMA (G.711)
PCMA
8
1
ITU-T G.711 PCM A-Law audio 64 kbit/s
8000
G.722
G722
9
1
ITU-T G.722 audio 64 kbit/s. Usually the codec in use for TopView voice calls. It is of excellent quality.
8000
G.723
G723
4
1
Obsoleted codec superseded by G726
8000
G.726-16
G726
104
1
ITU-T G.726 audio 16 kbit/s
8000
G.726-24
G726
105
1
ITU-T G.726 audio 24 kbit/s
8000
G.726-32
G726
106
1
ITU-T G.726 audio 32 kbit/s
8000
G.726-40
G726
107
1
ITU-T G.726 audio 40 kbit/s
8000
G.728
G728
15
1
ITU-T G.728 audio 16 kbit/s
8000
G.729
G729
18
1
ITU-T G.729 and G.729a audio 8 kbit/s; Annex B is implied unless the annexb=no parameter is used
8000
GSM
GSM
3
1
European GSM Full Rate audio 13 kbit/s (GSM 06.10)
8000
iLBC
iLBC
98
1
Internet low Bitrate Codec 13.33 or 15.2 kbit/s
8000
L16 (2 channel)
L16
10
2
Linear PCM 16-bit stereo audio
44100
L16
L16
11
1
Linear PCM 16-bit audio
44100
opus
opus
120
1
Opus audio
48000
SPEEX-Narrow
SPEEX
97
1
Speex audio
8000
SPEEX-Wideband
SPEEX
100
1
Speex audio
16000
SPEEX-Dynamic
SPEEX
108
1
Speex audio
32000

Reference codecs on Wikipedia: RTP audio video profile.

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