Codecs used in TopView VOIP notifications

As of TopView 6.30, VOIP configurations allow the specification of call codecs. 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?

Since TopView’s voice notifications utilize audio, codecs are used to encode and decode the notification message. Different VOIP providers can provide and support different audio codecs, and some of them play better on certain types of connections.

Most VOIP providers and endpoints within the same region support the same codecs.

If you notice poorer than expected audio quality over the call, you may find a different codec that will provide better quality.

TopView supports the following codecs:

NameAlt. namePayload typeNo. of channelsRate (Hz)Ratet (Hz)
PCMU (G.711)PCMU01ITU-T G.711 PCM ยต-Law audio 64 kbit/s8000
PCMA (G.711)PCMA81ITU-T G.711 PCM A-Law audio 64 kbit/s8000
G.722G72291ITU-T G.722 audio 64 kbit/s. Usually the codec in use for TopView voice calls. It is of excellent quality.8000
G.723G72341Obsoleted codec superseded by G7268000
G.726-16G7261041ITU-T G.726 audio 16 kbit/s8000
G.726-24G7261051ITU-T G.726 audio 24 kbit/s8000
G.726-32G7261061ITU-T G.726 audio 32 kbit/s8000
G.726-40G7261071ITU-T G.726 audio 40 kbit/s8000
G.728G728151ITU-T G.728 audio 16 kbit/s8000
G.729G729181ITU-T G.729 and G.729a audio 8 kbit/s; Annex B is implied unless the annexb=no parameter is used8000
GSMGSM31European GSM Full Rate audio 13 kbit/s (GSM 06.10)8000
iLBCiLBC981Internet low Bitrate Codec 13.33 or 15.2 kbit/s8000
L16 (2 channel)L16102Linear PCM 16-bit stereo audio44100
L16L16111Linear PCM 16-bit audio44100
opusopus1201Opus audio48000
SPEEX-NarrowSPEEX971Speex audio8000
SPEEX-WidebandSPEEX1001Speex audio16000
SPEEX-DynamicSPEEX1081Speex audio32000