Bandwidth used by the different codecs

When you are using Voice over IP, the used VoIPVoice over Internet protocol - A digital telephone system that uses the internet as the transmission medium, rather than the PSTN. phones and PBXPrivate Branch Exchange - System that connects telephone extensions and switches calls. can use different so called codecs. The consumption of bandwidth depends on which codec you use.

The following table gives you a short overview of the bandwidth consumption of the different codecs. On the page from, you can also find a bandwidth calculator tool.

codec name bandwidth (incl. overhead) bandwidth for 5 concurrent calls quality
G.711 a/u-law PCM 80 kbit/s 512 kbit/s ISDNIntegrated services digital network - A technology enabling digital transmission of data and voice signals over a telephone network.
G.729 CS-CELP 32 kbit/s 200 kbit/s good
iLBC iLBC 32 kbit/s 200 kbit/s good
G.723.1 MP-MLQ 21 kbit/s 110 kbit/s average
G.723 A-CELP 15 kbit/s 80 kbit/s average
GSM fullrate GSM 13 kbit/s 80 kbit/s average
G.726 AD-PCM 55 kbit/s 386 kbit/s GSM
SpeeX SpeeX 4 - 15 kbit/s 25 - 80 kbit/s variable